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Exercise 1271Calculus › Single-variable calculus › Differentiation › Mean Value TheoremL1Added 4 Nov 2026

Bounding $f(b)-f(a)$

#MVT#bound#interval

Statement

Let ff be C1C^1 on [0,1][0,1] with ∣f′∣≤2|f'|\le2. Show that ∣f(1)−f(0)∣≤2|f(1)-f(0)|\le2.

Hint

Apply MVT.

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Solution

MVT. f(1)−f(0)=f′(c)f(1)-f(0)=f'(c) for some c∈]0,1[c\in]0,1[, so ∣f(1)−f(0)∣≤2|f(1)-f(0)|\le2.

Conclusion. The inequality holds.