Proof that a function with bounded derivative is Lipschitz
Proof
We bound each difference quotient with the mean value theorem.
- Let . We must show .
- If , both sides are . The inequality is symmetric in and , so we may assume .
- Since is an interval, every with lies in . So .
- Each is an interior point of , because the open interval contains and lies in .
- So is differentiable on , with there. Also is continuous on .
- By the mean value theorem, there is with .
- Taking absolute values, , by step 5.
- This holds for all , so is Lipschitz with constant .
Idea
The mean value theorem says each chord slope of equals a value of . If every value of has size at most , every chord slope does too. That is exactly the Lipschitz condition.
Reading path
To understand this page from the ground up, read these 137 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 approximation property of the supremum, Proof that every sequence has a monotone subsequence, by peaks, Proof of the commutativity of addition by induction, Proof of the epsilon-delta form of continuity, Proof that there is a natural number n with 1/n below any positive epsilon, Proof that the reals form an ordered field, with the Cauchy sequence construction, Proof of the double negation law by a truth table, Proof of the extreme value theorem by the Bolzano–Weierstrass theorem, Proof of the uniqueness of limits, Proof of strong induction from ordinary induction, Proof of the limit of a product of sequences, Proof that the absolute value is multiplicative, Proof of the squeeze theorem for sequences, Proof of the linearity of differentiation, Proof of the sequential characterization of limits, Proof of the triangle inequality for real numbers, Proof of the epsilon-N definition of the limit of a sequence, Proof of Fermat's theorem on stationary points, Proof that limits preserve non-strict inequalities, 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 Archimedean property in an Archimedean ordered field, 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 of the boundedness theorem by Bolzano–Weierstrass, Proof of the mean value theorem from Rolle's theorem, Proof of the constant multiple rule.
- Construction of the reals from Cauchy sequences concept
- Definition by recursion concept
- Element definition
- Integers object
- Limit point of a set definition
- Lipschitz continuity definition
- Local maximum definition
- Mathematical induction concept
- Natural numbers object
- Ordered field definition
- Peano axioms concept
- Proposition concept
- Rational numbers object
- Real numbers object
- Sequence definition
- Set bounded above definition
- Set definition
- Ring of integers statement
- Limit of a function definition
- Local minimum definition
- Archimedean ordered field definition
- Successor function 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
- Ordered pair definition
- Continuity at a point definition
- Derivative definition
- Addition of natural numbers definition
- Proof of the Archimedean property in an Archimedean ordered field proof
- The rationals form a field statement
- Biconditional definition
- The successor function is injective statement
- Truth table concept
- Zero is not a successor statement
- Modus ponens concept
- Universal quantifier definition
- Bounded sequence definition
- Limit of a sequence definition
- Monotone sequence definition
- Completeness axiom statement
- Cartesian product definition
- Continuous function definition
- Differentiable function definition
- Archimedean property statement
- Proof of the commutativity of addition by induction proof
- Subset definition
- Order on the natural numbers definition
- The rationals form an ordered field statement
- Propositional logic concept
- Mathematical proof concept
- Convergent sequence definition
- Sequential continuity definition
- Binary relation definition
- Order on the reals definition
- Commutativity of addition statement
- Proof of strong induction from ordinary induction proof
- Tautology definition
- Antisymmetric relation definition
- Reflexive relation definition
- Transitive relation definition
- Interval definition
- Strong induction statement
- Logical equivalence definition
- Preorder definition
- Proof of the epsilon-delta form of continuity proof
- Proof of the epsilon-delta form of the limit of a function proof
- Proof of the well-ordering principle from strong induction proof
- Proof of the double negation law by a truth table proof
- Partial order definition
- Epsilon-delta definition of continuity statement
- Epsilon-delta definition of a limit statement
- Well-ordering principle statement
- Double negation law statement
- Total order definition
- Proof by contradiction concept
- Proof that every sequence has a monotone subsequence, by peaks proof
- Proof that the reals form an ordered field, with the Cauchy sequence construction proof
- Every sequence has a monotone subsequence statement
- The reals form an ordered field statement
- Absolute value definition
- Proof of the approximation property of the supremum proof
- Proof of the triangle inequality for real numbers proof
- Proof that the absolute value is multiplicative proof
- Proof of the epsilon-N definition of the limit of a sequence proof
- Approximation property of the supremum statement
- Triangle inequality statement
- Absolute value is multiplicative statement
- Epsilon-N definition of the limit of a sequence statement
- Proof that the reals are Archimedean from the completeness axiom proof
- Proof of the limit of a sum of sequences proof
- Proof of the squeeze theorem for sequences proof
- Proof of the uniqueness of limits proof
- Proof that limits preserve non-strict inequalities proof
- The reals are Archimedean statement
- Proof that convergent sequences are bounded proof
- Proof of the monotone convergence theorem for sequences proof
- Proof that there is a natural number n with 1/n below any positive epsilon proof
- Limit of a sum of sequences statement
- Uniqueness of limits statement
- Limits preserve non-strict inequalities statement
- Squeeze theorem statement
- Convergent sequences are bounded statement
- Monotone convergence theorem for sequences statement
- Proof of the limit of a product of sequences proof
- There is a natural number n with 1/n below any positive epsilon statement
- Proof that a decreasing sequence bounded below converges proof
- Decreasing sequence bounded below converges statement
- Proof of the sequential characterization of limits proof
- Proof that continuity is equivalent to sequential continuity proof
- Limit of a product of sequences statement
- Continuity is equivalent to sequential continuity statement
- Sequential characterization of limits statement
- Proof of the Bolzano–Weierstrass theorem by a monotone subsequence proof
- Proof of the linearity of differentiation proof
- Bolzano–Weierstrass theorem statement
- Linearity of differentiation statement
- Proof of the boundedness theorem by Bolzano–Weierstrass proof
- Proof of the constant multiple rule proof
- Boundedness theorem statement
- Constant multiple rule statement
- Proof of the extreme value theorem by the Bolzano–Weierstrass theorem proof
- Extreme value theorem statement
- Proof of Fermat's theorem on stationary points proof
- Fermat's theorem on stationary points statement
- Proof of Rolle's theorem proof
- Rolle's theorem statement
- Proof of the mean value theorem from Rolle's theorem proof
- Mean value theorem statement
- Proof that a function with bounded derivative is Lipschitz proof
Where this leads
1 page builds on this one.
Further reading
About this page
| Tag | HD08YKADB1 |
|---|---|
| URI | m2://HD08YKADB1 |
| Kind | proof |
| Writing | W0 stub |
| MSC | 26A16 |
| Proves | A function with bounded derivative is Lipschitz |
| Uses | Mean value theorem, Lipschitz continuity, Interval |
| Changed | 4 November 2026 |
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