Question

Let f(x) = x³ + bx² + cx +d ; 0 < b²< c then f(x) :

• A. Is strictly increasing
• B. Has local maxima
• C. Has local minima
• D. Is bounded curve

Answer 1

Answer: (A)

Is strictly increasing

Answer 2

f(x) = x³ + bx² + cx + d

$\frac{dy}{dx}$ = 3x² + 2bx + c

D = 4b² – 4 × 3 × c = 4(b² – 3c ), b² < c = – ve