A point on a curve is said to be an extremum if it is a local minimum or a local maximum. The number of distinct extrema for the curve 3x4 – 16x3 + 24x2 + 37
(A) 0
(B) 1
(C) 2
(D) 3
Answer: (B)
Explanation: f(x) = 3x 4 – 16x3 + 242 +37
—> f ‘(x) = 12x3 -48x2 + 48x
—> f”(x) = 36x2 -96x + 48
f‘(x)=0 —> =12x(x2 – 4x +4) = 12x(x-2)2
f‘(x) is negative for all x0
—> f(x) is decreasing to the left of 0 and increasing to the right of 0
—> f(x) has only one minimum (extrema) at x=0
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