NDA || Maths || Limit_and_Differentiation

If f(x) = sin (cos x), then f’(x) is equal to

Find the value of

Let f(x) be a function such that What is  dx equal to?

The differential equation of minimum order by elimination the arbitral constant A and C in the equation  is

Find the intervals in which f (x) = 2x³ – 3x² -36x + 7 is strictly decreasing