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CUET · MATHS · PYQ PAPER 2025

The greatest possible value of \(a\) such that the function\(f(x)=x^2+a x+1\) is always decreasing in the interval \([1,2]\), is:

  1. A -2
  2. B -4
  3. C 2
  4. D 4
Verified Solution

Answer & Solution

Correct Answer

(B) -4

Step-by-step Solution

Detailed explanation

\(f'(x) = 2x+a\) For \(f(x)\) to be decreasing on \([1,2]\), \(f'(x) \le 0\) for all \(x \in [1,2]\). Since \(f'(x)\) is increasing, its maximum on \([1,2]\) is at \(x=2\). \(f'(2) \le 0 \implies 2(2)+a \le 0\) \(4+a \le 0 \implies a \le -4\) Greatest possible value of \(a\) is…
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