Let g (x) = 2x sin x . (a) Find g′(x) . (b) Find the gradient of the graph of g at x = π .

a)   f'(x)=uv'+vu'     if    f(x)= uv

u=2x  u'=2  v=sin(x)   v'=cos(x)

g'(x)=2x cos(x) +2sin(x)

b)   g'(π) = 2π cos(π)+2sin(π)  = 2 π (-1) + 2 (0)

      g'(π) = -2π