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Question: Answered & Verified by Expert
Rolle's theorem is not applicable in which one of the following cases?
MathematicsContinuity and DifferentiabilityKCETKCET 2019
Options:
  • A \( f(x)=x^{2}-x \) in \( [0,1] \)
  • B \( f(x)=[x] \) in \( [2.5,2.7] \)
  • C \( f(x)=x^{2}-4 x+5 \) in \( [1,3] \)
  • D \( f(x)=|x| \) in \( [-2,2] \)
Solution:
1695 Upvotes Verified Answer
The correct answer is: \( f(x)=|x| \) in \( [-2,2] \)
\(f(x)=x^{2}-4 x+5\)
\(x \in[1,3]\)
\(\begin{aligned} f(1) &=1-4+5 \\ &=2 \\ f(3) &=9-12+5 \\ &=2 \\ f^{\prime}(x) &=2 x-4 \\ \lim _{h \rightarrow 0} f^{\prime}(x) &=\lim _{h \rightarrow 0}(2 x-4) \\ &=-4 \end{aligned}\)
\(\therefore\) IInd condition of rolls theorem is not satisfied.
\(\therefore\) Role theorem not applicable

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