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KCET · Maths · Continuity and Differentiability

Rolle's theorem is not applicable in which one of the following cases?

  1. A \( f(x)=x^{2}-x \) in \( [0,1] \)
  2. B \( f(x)=[x] \) in \( [2.5,2.7] \)
  3. C \( f(x)=x^{2}-4 x+5 \) in \( [1,3] \)
  4. D \( f(x)=|x| \) in \( [-2,2] \)
Verified Solution

Answer & Solution

Correct Answer

(D) \( f(x)=|x| \) in \( [-2,2] \)

Step-by-step Solution

Detailed explanation

\(f(x)=x^{2}-4 x+5\)
\(x \in[1,3]\)
\(\begin{aligned} f(1) &=1-4+5 \\ &=2 \\ f(3) &=9-12+5 \\ &=2 \\ f^{\prime}(x) &=2 x-4 \\ \lim _{h \rightarrow 0} f^{\prime}(x) &=\lim _{h \rightarrow 0}(2 x-4) \\ &=-4 \end{aligned}\)
\(\therefore\) IInd condition of rolls theorem is not satisfied.
\(\therefore\) Role theorem not applicable