Question

The length of a longest interval in which the function 3sin x - 4 sin³ x is increasing, is

(a) pi/3

(b) pi/2

(c) 3pi/2

(d) pi

Answer 1

Correct option (a) pi/3

Explanation :

Let f(x) = 3sin x - 4 sin³ x = sin 3x

The longest interval in which sin x is increasing, is of length pi.

So, the length of largest interval in which f(x) = sin 3x is increasing, is pi/3