The question is attached above

Asked by sudhanshubhushanroy | 8th Nov, 2017, 01:07: PM

Expert Answer:

f'(x) will be a quadratic equation with imaginary roots and coeff of x2 is positive so it will lie above the x axis
 
so  it is always positive.

Answered by Arun | 8th Dec, 2017, 05:16: PM