Question

Find the derivative of the following functions (it is to be understood that a, b, c, d, p, q, r and s are fixed nonzero constants and m and n are integers): (x2+1) cosx

Answer 1

Let f(x)= (x2+1) cos x
By Product rule,
f'(x)= (x2+1) $\frac{d}{dx}$ (cos x) + cos x$\frac{d}{dx}$(x2+1)
= (x2+1)(-sinx) + cos x(2x)
=-x2 sin x -sin x + 2xcos x