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WBJEE · Maths · Continuity and Differentiability

Suppose that \(f(x)\) is a differentiable function such that \(f^{\prime}(x)\) is continuous, \(f^{\prime}(0)=1\) and \(f^{\prime \prime}(0)\) does not exist. Let \(g(x)=x f^{\prime}(x) .\) Then,

  1. A \(g^{\prime}(0)\) does not exist
  2. B \(g^{\prime}(0)=0\)
  3. C \(g^{\prime}(0)=1\)
  4. D \(g^{\prime}(0)=2\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(g^{\prime}(0)=1\)

Step-by-step Solution

Detailed explanation

Given, \(f^{\prime}(0)=1\) and \(f^{\prime \prime}\) " (0) does not exist. Also, given \(g(x)=x f^{\prime}(x)\) \(\therefore \quad g^{\prime}(x)=x f^{\prime \prime}(x)+f^{\prime}(x)\) Put \(x=0,\) we get…