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CUET · MATHS · PYQ PAPER 2025

The function \(f(x)=-\frac{3}{4} x^4-8 x^3-\frac{45}{2} x^2+163\) has a local maxima at

  1. A x = 0 and x = 3
  2. B x = - 3 and x = - 5
  3. C x = 0 and x = - 5
  4. D x = - 3
Verified Solution

Answer & Solution

Correct Answer

(C) x = 0 and x = - 5

Step-by-step Solution

Detailed explanation

\(f'(x) = -3x^3 - 24x^2 - 45x\) \(-3x(x^2 + 8x + 15) = 0\) \(-3x(x+3)(x+5) = 0 \Rightarrow x = 0, x = -3, x = -5\) \(f''(x) = -9x^2 - 48x - 45\) \(f''(0) = -9(0)^2 - 48(0) - 45 = -45 \(f''(-3) = -9(-3)^2 - 48(-3) - 45 = -81 + 144 - 45 = 18 > 0\)…
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