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CUET · MATHS · PYQ PAPER 2025

If \(f(x)=a \log _e|x|+b x^2+x\) has critical points at \(x=-2\) and \(x=1\), then

  1. A \(a+2 b=0\)
  2. B \(a-2 b=0\)
  3. C \(a+4 b=0\)
  4. D \(a-4 b=0\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(a+4 b=0\)

Step-by-step Solution

Detailed explanation

\(f'(x) = \frac{a}{x} + 2bx + 1\) \(f'(-2) = \frac{a}{-2} + 2b(-2) + 1 = 0 \Rightarrow -\frac{a}{2} - 4b + 1 = 0 \Rightarrow a + 8b = 2\) \(f'(1) = \frac{a}{1} + 2b(1) + 1 = 0 \Rightarrow a + 2b = -1\) \((a+8b)-(a+2b) = 2 - (-1) \Rightarrow 6b = 3 \Rightarrow b = \frac{1}{2}\)…
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