Proof of the implicit function theorem from the inverse function theorem
Builds on Inverse function theoremC^k function characterised by continuous derivativesJacobian matrixDeterminant of a block triangular matrixDeterminant of a transposeA matrix is invertible iff its determinant is a unitDerivative of the inverse function in several variablesContinuous partial derivatives imply differentiabilityChain rule in several variablesContinuity in R^n
Proof
We apply the inverse function theorem to the map .
- Let , and be as in the statement. Define by .
- The components of are the coordinates and the components of . So is of class C^1, and its Jacobian matrix at is the block matrix .
- By the determinant of a block triangular matrix, applied to the transpose, and since a matrix and its transpose have the same determinant, .
- Since is invertible, its determinant is not zero, so .
- By the inverse function theorem with , there are open sets with and with . The map is a bijection from onto , with inverse of class .
- The map does not change the first coordinate . So does not change it either: for some . The map is of class , since its components are components of .
- For , the equation says .
- Since is open, there is such that every point within distance of lies in . Let and . If and , then . So .
- Let . The map is continuous and is open, so the first condition defines an open set. On it, is continuous, and is open. So is open.
- We have , since . So , and .
- Define by . By step 9, . By step 7, for .
- Conversely, let with . Then by step 8, and . Also .
- Since is injective on , we get . With step 11: for , if and only if .
- The function is unique. If has the same property, then with , so by step 13.
- The function is the composition of with the map . By the chain rule, , which is continuous. So is of class .
- Let . The maps and are differentiable, by continuous partials. By the derivative of the inverse function, is invertible. By step 3 and the determinant criterion, is invertible.
- Differentiate the identity on the open set with the chain rule. This gives .
- Multiplying on the left by gives .
Idea
The map keeps and records the value of . Its derivative is invertible exactly when is, so it has a local inverse. Reading off the inverse at the points gives the solution of , and differentiating gives the formula for .
Reading path
To understand this page from the ground up, read these 448 pages in order. The foundations come first. The path takes the proofs Proof of the limit of a sum of sequences, Proof of Rolle's theorem, Proof of the derivative of a map into R^n by components, Proof of the approximation property of the supremum, Proof that every sequence has a monotone subsequence, by peaks, Proof of the decomposition of a permutation into transpositions, Proof that the symmetric group is generated by transpositions, Proof of the Laplace expansion along a column by transposition, Proof that open sets are the sets that are neighbourhoods of all their points, Proof that closed balls are closed, Proof of the diameter characterisation of Cauchy sequences, Proof of the commutativity of addition by induction, Proof of the Lebesgue number lemma by a finite cover of balls, Proof of the epsilon-delta form of continuity, Proof that equivalence classes form a partition, Proof of the triangle inequality for norms, Proof of the sum of a finite geometric series, Proof that a complex number times its conjugate is the square of its modulus, Proof of the Cauchy–Schwarz inequality, Proof of the Heine–Borel theorem by sequential compactness, Proof that there is a natural number n with 1/n below any positive epsilon, Proof of the chain rule in several variables, Proof that the determinant is multiplicative by expanding the rows, Proof that permuting rows multiplies the determinant by the sign, Proof that closed subsets of complete spaces are complete, Proof of the derivative as a little-o approximation, Proof that disjoint cycles commute, Proof of the equality of complex numbers, Proof that a matrix is invertible iff its determinant is a unit, Proof that a linear map between normed spaces is continuous if and only if it is bounded, Proof of the determinant of a block triangular matrix by the Leibniz formula, Proof that a function is bijective iff it has a two-sided inverse, Proof that the reals form an ordered field, with the Cauchy sequence construction, Proof of continuity via closed sets, Proof that a matrix with two equal rows has determinant zero, Proof of the double negation law by a truth table, Proof of the extreme value theorem by the Bolzano–Weierstrass theorem, Proof that compact subsets of a metric space are bounded, Proof of the Laplace expansion along a row by the Leibniz formula, Proof that compactness and sequential compactness agree in metric spaces, Proof that subsequences of a convergent sequence converge to the same limit, Proof of the uniqueness of limits, Proof that the coordinate map is a linear isomorphism, Proof of strong induction from ordinary induction, Proof that linear maps on finite-dimensional normed spaces are continuous, Proof that the determinant of a transpose equals the determinant, Proof of the laws of exponents in a group, Proof of the limit of a product of sequences, Proof of the inverse in terms of the adjugate, Proof that the absolute value is multiplicative, Proof of the squeeze theorem for sequences, Proof of the existence of square roots of nonnegative reals, Proof of the chain rule for a composition with a curve, Proof of the linearity of differentiation, Proof that a continuous image of a compact set is compact, Proof that compact subsets of a Hausdorff space are closed, Proof that the composition of continuous maps is continuous, Proof of epsilon-delta continuity at a point in metric spaces, Proof of the sequential characterization of limits, Proof of the description of the open sets of a metric space, Proof of the Banach fixed point theorem by iteration, Proof of the triangle inequality for real numbers, Proof that an intersection of subgroups is a subgroup, Proof of the epsilon-N definition of the limit of a sequence, Proof that compactness of a subset can be tested with open sets of the ambient space, Proof that the sign is a homomorphism, Proof of the existence of the infimum by negation, Proof of the equivalence of norms in finite dimension by compactness of the unit sphere, Proof of the determinant of the inverse, Proof that every spanning set contains a basis, by Zorn's lemma, Proof that the determinant of the identity matrix is one, Proof of Fermat's theorem on stationary points, Proof that limits preserve non-strict inequalities, Proof of the inverse function theorem by the contraction mapping principle, Proof that closed sets contain their limits, Proof of Zorn's lemma, Proof that metric spaces are Hausdorff, Proof that the derivative gives the directional derivatives, Proof that differentiable functions are continuous, Proof of the decomposition of a permutation into disjoint cycles, Proof of the product of a matrix and its adjugate by Laplace expansion, Proof of the sequence characterisation of uniform continuity, Proof of the epsilon-delta form of the limit of a function, Proof of the well-ordering principle from strong induction, Proof of the Bolzano–Weierstrass theorem by a monotone subsequence, Proof of the division algorithm, Proof of the Archimedean property in an Archimedean ordered field, Proof of the sign of a cycle, Proof that finite-dimensional normed spaces are complete, Proof that a continuous real function on a compact set attains its bounds, Proof of the Leibniz formula from the defining properties of the determinant, Proof of the uniqueness of inverses, Proof of the derivative of a map into a product, Proof that a decreasing sequence bounded below converges, Proof that the reals are Archimedean from the completeness axiom, Proof that convergent sequences are bounded, Proof of the monotone convergence theorem for sequences, Proof that continuity is equivalent to sequential continuity, Proof that the determinant is multilinear in the rows, Proof that open balls are open, Proof of the boundedness theorem by Bolzano–Weierstrass, Proof that Lipschitz maps are uniformly continuous, Proof that C^k functions are characterised by continuous derivatives, Proof that continuous partial derivatives imply differentiability, Proof that a set is open if and only if its complement is closed, Proof of the subgroup criterion, Proof of the mean value theorem from Rolle's theorem, Proof of continuity via open sets in metric spaces, Proof of the mean value inequality, Proof of the constant multiple rule.
- Affine combination concept
- Basis concept
- Binary operation definition
- Complex numbers object
- Complex numbers as pairs of reals concept
- Construction of the reals from Cauchy sequences concept
- Coordinate space object
- Coordinate vector concept
- Cycle notation concept
- Definition by recursion concept
- Divisibility definition
- Element definition
- Euclidean metric example
- Euclidean space object
- Extended real number line object
- Function concept
- Function composition concept
- Group concept
- Identity matrix object
- Imaginary unit object
- Inner product concept
- Inner product space concept
- Integers object
- Limit point of a set definition
- Linear isomorphism concept
- Linear map concept
- Local maximum definition
- Mathematical induction concept
- Matrix definition
- Multilinear map concept
- Natural numbers object
- Norm concept
- Norm induced by an inner product concept
- Ordered field definition
- Peano axioms concept
- Permutation concept
- Permutation definition
- Proof of Zorn's lemma proof
- Proposition concept
- Rational numbers object
- Real numbers object
- Sequence definition
- Set bounded above definition
- Transposition concept
- Vector space definition
- p-metric on R^n example
- Identity element definition
- Real and imaginary parts definition
- Convex set definition
- Set definition
- Fréchet derivative definition
- Having a directional derivative definition
- Total derivative concept
- Function of several variables concept
- Vector-valued function concept
- Group homomorphism definition
- Ring definition
- Subgroup definition
- Symmetric group definition
- Ring of integers statement
- Limit of a function definition
- Local minimum definition
- Block matrix definition
- Matrix multiplication definition
- Square matrix definition
- Transpose definition
- Successor function definition
- Archimedean ordered field definition
- Conjunction definition
- Disjunction definition
- Implication definition
- Negation definition
- Predicate definition
- The reals form a field statement
- Real sequence definition
- Subsequence definition
- Infimum definition
- Supremum definition
- Inner product definition
- Linear combination definition
- Linear map definition
- Linear subspace definition
- Norm definition
- p-norm on R^n example
- Inverse element definition
- Complex conjugate definition
- Empty set object
- Family of sets definition
- Ordered pair definition
- Differentiable function of several variables concept
- Partial derivative concept
- Limit of a function of several variables concept
- Transposition definition
- Unit of a ring definition
- Parametrised curve concept
- Intersection definition
- Union definition
- Continuity at a point definition
- Derivative definition
- Proof that an intersection of subgroups is a subgroup proof
- Set-builder notation concept
- Invertible matrix definition
- Addition of natural numbers definition
- Biconditional definition
- Truth table concept
- Modus ponens concept
- Existential quantifier definition
- The rationals form a field statement
- Universal quantifier definition
- Proof of the Archimedean property in an Archimedean ordered field proof
- The successor function is injective statement
- Zero is not a successor statement
- Bounded sequence definition
- Cauchy sequence definition
- Geometric sequence definition
- Limit of a sequence definition
- Monotone sequence definition
- Inner product space definition
- Linear independence definition
- Composition of linear maps definition
- Linear isomorphism definition
- Linear span definition
- Multilinear map definition
- Normed vector space definition
- Completeness axiom statement
- Cartesian product definition
- Gradient concept
- Jacobian matrix concept
- Proof of the equality of complex numbers proof
- Disjoint sets definition
- Proof of the uniqueness of inverses proof
- Partial derivative definition
- Continuity in R^n definition
- Differentiable function of several variables definition
- Union of a family of sets definition
- Continuous function definition
- Differentiable function definition
- Axiom of extensionality statement
- Subset definition
- Mathematical proof concept
- Proof of the derivative as a little-o approximation proof
- Proof of the commutativity of addition by induction proof
- Archimedean property statement
- Uniqueness quantifier definition
- Order on the natural numbers definition
- Propositional logic concept
- The rationals form an ordered field statement
- Proof of the sum of a finite geometric series proof
- Convergent sequence definition
- Sequential continuity definition
- Norm induced by an inner product definition
- Spanning set definition
- Alternating multilinear map definition
- Equality of complex numbers statement
- Higher partial derivatives definition
- Binary relation definition
- Jacobian matrix definition
- Uniqueness of inverses statement
- Differentiable on an open set definition
- Universal set definition
- Partition of a set definition
- Topological space definition
- Derivative as a little-o approximation statement
- Proof of the derivative of a map into R^n by components proof
- Order on the reals definition
- Tautology definition
- Commutativity of addition statement
- Determinant definition
- Proof of strong induction from ordinary induction proof
- Finite-dimensional vector space definition
- Sum of a finite geometric series statement
- Basis definition
- Antisymmetric relation definition
- Reflexive relation definition
- Symmetric relation definition
- Transitive relation definition
- Jacobian determinant definition
- Iterated derivative definition
- Sequential compactness definition
- Complement definition
- Function definition
- Proof of the laws of exponents in a group proof
- Proof of the subgroup criterion proof
- Subspace topology definition
- Interval definition
- Proof that a matrix with two equal rows has determinant zero proof
- Proof that the determinant of the identity matrix is one proof
- Logical equivalence definition
- Coordinate vector definition
- Strong induction statement
- Minor definition
- Proof that the determinant is multilinear in the rows proof
- Equivalence relation definition
- Preorder definition
- Codomain definition
- Function composition definition
- Identity function definition
- Injective function definition
- Choice function definition
- Image of a set definition
- Preimage of a set definition
- Restriction of a function definition
- Subgroup criterion statement
- Proof of the epsilon-delta form of continuity proof
- Laws of exponents in a group statement
- Proof of the epsilon-delta form of the limit of a function proof
- Determinant of a matrix with two equal rows statement
- Determinant of the identity matrix statement
- Metric space definition
- Determinant is multilinear in the rows statement
- Cofactor definition
- Proof of the well-ordering principle from strong induction proof
- Proof of the double negation law by a truth table proof
- Partial order definition
- Left inverse definition
- Right inverse definition
- Surjective function definition
- Axiom of choice statement
- Proof that disjoint cycles commute proof
- Equivalence class definition
- Epsilon-delta definition of continuity statement
- Intersection of subgroups is a subgroup statement
- Subspace metric definition
- Epsilon-delta definition of a limit statement
- Closed ball definition
- Convergence of a sequence in a metric space definition
- Lipschitz map definition
- Open ball definition
- Triangle inequality for a metric statement
- Adjugate matrix definition
- Double negation law statement
- Diameter of a set definition
- Well-ordering principle statement
- Maximal element definition
- Total order definition
- Upper bound definition
- Bijective function definition
- Proof that equivalence classes form a partition proof
- Disjoint cycles commute statement
- Subgroup generated by a subset definition
- Metric topology definition
- Bounded set definition
- Contraction mapping definition
- Proof by contradiction concept
- Proof of the division algorithm proof
- Proof of the diameter characterisation of Cauchy sequences proof
- Proof that every sequence has a monotone subsequence, by peaks proof
- Chain definition
- Proof that a function is bijective iff it has a two-sided inverse proof
- Equivalence classes form a partition statement
- Open set definition
- Division algorithm statement
- Epsilon characterisation of Cauchy sequences statement
- Proof that the reals form an ordered field, with the Cauchy sequence construction proof
- Every sequence has a monotone subsequence statement
- Bijective iff it has a two-sided inverse statement
- Hausdorff space definition
- Closed set definition
- Open cover definition
- Continuous map of topological spaces definition
- Proof that open sets are the sets that are neighbourhoods of all their points proof
- Proof of the decomposition of a permutation into disjoint cycles proof
- Proof that the derivative gives the directional derivatives proof
- Zorn's lemma statement
- Equivalent metrics definition
- Proof of the description of the open sets of a metric space proof
- Complete metric space definition
- The reals form an ordered field statement
- Compact space definition
- Proof that a set is open if and only if its complement is closed proof
- Proof that the composition of continuous maps is continuous proof
- Open sets characterised by neighbourhoods statement
- Derivative gives the directional derivatives statement
- Decomposition of a permutation into disjoint cycles statement
- Equivalent norms definition
- Open sets of a metric space statement
- Proof that the coordinate map is a linear isomorphism proof
- Absolute value definition
- Proof that every spanning set contains a basis, by Zorn's lemma proof
- Proof of the approximation property of the supremum proof
- Proof of the existence of the infimum by negation proof
- Proof of the existence of square roots of nonnegative reals proof
- Complement of an open set is closed statement
- Composition of continuous maps is continuous statement
- Continuous linear map definition
- Compact set definition
- Continuity at a point of a topological space definition
- Proof of the decomposition of a permutation into transpositions proof
- Banach space definition
- Proof that closed sets contain their limits proof
- Proof of the triangle inequality for real numbers proof
- Proof that the absolute value is multiplicative proof
- Proof that closed balls are closed proof
- Proof that open balls are open proof
- Every spanning set contains a basis statement
- Isomorphism with the coordinate space statement
- Proof of the epsilon-N definition of the limit of a sequence proof
- Existence of square roots of nonnegative reals statement
- Approximation property of the supremum statement
- Existence of the infimum statement
- Proof that compactness of a subset can be tested with open sets of the ambient space proof
- Proof of continuity via closed sets proof
- Decomposition of a permutation into transpositions statement
- Closed sets contain their limits statement
- Triangle inequality statement
- Absolute value is multiplicative statement
- Closed balls are closed statement
- Open balls are open statement
- Square root definition
- Epsilon-N definition of the limit of a sequence statement
- Proof that the reals are Archimedean from the completeness axiom proof
- Sign of a permutation definition
- Continuity via closed sets statement
- Modulus of a complex number definition
- Compactness via open covers statement
- Proof of the limit of a sum of sequences proof
- Proof that closed subsets of complete spaces are complete proof
- Proof of the uniqueness of limits proof
- Proof that the symmetric group is generated by transpositions proof
- Proof of epsilon-delta continuity at a point in metric spaces proof
- Proof of the squeeze theorem for sequences proof
- Proof of the Lebesgue number lemma by a finite cover of balls proof
- Proof of continuity via open sets in metric spaces proof
- Proof that limits preserve non-strict inequalities proof
- Proof that differentiable functions are continuous proof
- Proof that metric spaces are Hausdorff proof
- Proof that convergent sequences are bounded proof
- The reals are Archimedean statement
- Proof that subsequences of a convergent sequence converge to the same limit proof
- Proof of the monotone convergence theorem for sequences proof
- Proof that compact subsets of a Hausdorff space are closed proof
- Proof that a complex number times its conjugate is the square of its modulus proof
- Proof that a continuous image of a compact set is compact proof
- The symmetric group is generated by transpositions statement
- Proof that the sign is a homomorphism proof
- Closed subsets of complete spaces are complete statement
- Proof of the sign of a cycle proof
- Lebesgue number lemma statement
- Epsilon-delta continuity in metric spaces statement
- Proof that compact subsets of a metric space are bounded proof
- Metric spaces are Hausdorff statement
- Proof that compactness and sequential compactness agree in metric spaces proof
- Differentiable functions are continuous statement
- Limit of a sum of sequences statement
- Proof of the sequence characterisation of uniform continuity proof
- Uniqueness of limits statement
- Proof of the triangle inequality for norms proof
- Limits preserve non-strict inequalities statement
- Convergent sequences are bounded statement
- Squeeze theorem statement
- Proof that there is a natural number n with 1/n below any positive epsilon proof
- Subsequences of a convergent sequence converge to the same limit statement
- Monotone convergence theorem for sequences statement
- A complex number times its conjugate statement
- Compact subsets of a Hausdorff space are closed statement
- Sign of a cycle statement
- Continuous image of a compact set is compact statement
- Sign is a homomorphism statement
- Compactness and sequential compactness agree in metric spaces statement
- Continuity via open sets statement
- Compact subsets of a metric space are bounded statement
- Proof of the limit of a product of sequences proof
- Epsilon-delta uniform continuity statement
- Proof that permuting rows multiplies the determinant by the sign proof
- There is a natural number n with 1/n below any positive epsilon statement
- Proof that a decreasing sequence bounded below converges proof
- Triangle inequality for norms statement
- The sequence r^n tends to zero for |r| < 1 example
- Proof that a linear map between normed spaces is continuous if and only if it is bounded proof
- Permuting rows multiplies the determinant by the sign statement
- Proof of the Banach fixed point theorem by iteration proof
- Proof that Lipschitz maps are uniformly continuous proof
- Proof of the sequential characterization of limits proof
- Proof that continuity is equivalent to sequential continuity proof
- Proof of the Cauchy–Schwarz inequality proof
- Decreasing sequence bounded below converges statement
- Limit of a product of sequences statement
- Banach fixed point theorem statement
- Lipschitz maps are uniformly continuous statement
- Continuity is equivalent to sequential continuity statement
- Proof of the Leibniz formula from the defining properties of the determinant proof
- Sequential characterization of limits statement
- Proof of the Bolzano–Weierstrass theorem by a monotone subsequence proof
- Cauchy–Schwarz inequality statement
- Bounded linear maps are continuous statement
- Leibniz formula for determinants statement
- Proof of the linearity of differentiation proof
- Bolzano–Weierstrass theorem statement
- Proof of the derivative of a map into a product proof
- Proof of the determinant of a block triangular matrix by the Leibniz formula proof
- Linearity of differentiation statement
- Proof of the Heine–Borel theorem by sequential compactness proof
- Operator norm definition
- Proof of the Laplace expansion along a row by the Leibniz formula proof
- Proof that the determinant is multiplicative by expanding the rows proof
- Proof that the determinant of a transpose equals the determinant proof
- Proof of the boundedness theorem by Bolzano–Weierstrass proof
- Completeness of the real numbers statement
- Derivative of a map into a product statement
- Proof of the constant multiple rule proof
- Heine–Borel theorem statement
- Boundedness theorem statement
- Determinant of a block triangular matrix statement
- Determinant is multiplicative statement
- Laplace expansion along a row statement
- Determinant of a transpose statement
- Constant multiple rule statement
- Derivative of a map into R^n by components statement
- Proof of the determinant of the inverse proof
- Proof of the Laplace expansion along a column by transposition proof
- Proof of the extreme value theorem by the Bolzano–Weierstrass theorem proof
- Proof that a continuous real function on a compact set attains its bounds proof
- Extreme value theorem statement
- Determinant of the inverse statement
- Continuous real function on a compact set attains its bounds statement
- Laplace expansion along a column statement
- Proof of Fermat's theorem on stationary points proof
- Proof of the equivalence of norms in finite dimension by compactness of the unit sphere proof
- Proof of the product of a matrix and its adjugate by Laplace expansion proof
- Fermat's theorem on stationary points statement
- Equivalence of norms in finite dimension statement
- Product of a matrix and its adjugate statement
- Proof of Rolle's theorem proof
- Rolle's theorem statement
- Proof that linear maps on finite-dimensional normed spaces are continuous proof
- Proof that finite-dimensional normed spaces are complete proof
- Proof of the inverse in terms of the adjugate proof
- Linear maps on finite-dimensional spaces are continuous statement
- Finite-dimensional normed spaces are complete statement
- Proof of the mean value theorem from Rolle's theorem proof
- Inverse in terms of the adjugate statement
- Mean value theorem statement
- Proof that a matrix is invertible iff its determinant is a unit proof
- Proof of the chain rule in several variables proof
- Proof that continuous partial derivatives imply differentiability proof
- Chain rule in several variables statement
- A matrix is invertible iff its determinant is a unit statement
- Derivative of the inverse function in several variables statement
- Continuous partial derivatives imply differentiability statement
- Proof of the chain rule for a composition with a curve proof
- Chain rule for a composition with a curve statement
- Proof that C^k functions are characterised by continuous derivatives proof
- C^k function characterised by continuous derivatives statement
- Proof of the mean value inequality proof
- Mean value inequality statement
- Proof of the inverse function theorem by the contraction mapping principle proof
- Inverse function theorem statement
- Proof of the implicit function theorem from the inverse function theorem proof
Where this leads
22 pages build on this one.
- Lagrange multiplier with one constraint
- Implicit function theorem
- Implicit function theorem for a surjective derivative
- Implicit differentiation
- Lagrange multipliers
- Proof of the Lagrange multiplier rule with one constraint
- Proof of the implicit function theorem for a surjective derivative
- Augmented Lagrangian method
- Proof of the Lagrange multiplier theorem by the implicit function theorem
- Marshallian demand function
- Utility maximization problem
- Implicit function theorem in Banach spaces
- Lyapunov–Schmidt reduction
- Numerical continuation
- Sequential quadratic programming
- Differential-algebraic system of equations
- Backus–Gilbert method
- Regular value theorem
- Configuration space
- Lagrange multipliers for constraints
- Indirect utility function
- Adjoint state method
Further reading
- Web https://en.wikipedia.org/wiki/Inverse_function_theorem, Implicit function theorem
About this page
| Tag | 35SNAG4VF8 |
|---|---|
| URI | m2://35SNAG4VF8 |
| Kind | proof |
| Writing | W0 stub |
| MSC | 26B10 |
| Proves | Implicit function theorem |
| Uses | Inverse function theorem, C^k function characterised by continuous derivatives, Jacobian matrix, Determinant of a block triangular matrix, Determinant of a transpose, A matrix is invertible iff its determinant is a unit, Derivative of the inverse function in several variables, Continuous partial derivatives imply differentiability, Chain rule in several variables, Continuity in R^n |
| Changed | 4 November 2026 |
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