If the function \( f(x)=x^4-62x^2+ax+9 \) has a critical point at \( x=1 \), then \( a \) is equal to:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 120
A polynomial is differentiable everywhere, so a critical point is where \( f'(x)=0 \).
\( \displaystyle f'(x)=4x^3-124x+a \)
At x = 1,
\( \displaystyle 4-124+a=0 \)
\( \displaystyle a=120 \)
NCERT (2026-27 edition):
Maxima and Minima
