y=(4x+1)^3*sin(2x) - this is a product of two functions of x. It can be rewritten as y = u(x)*v(x) ; where u(x) = (4x+1)^3 and v(x) = sin(2x)
Using the product rule: dy/dx = u'(x)*v(x) + v'(x)*u(x) where the ' (prime) notation denotes the differential with respect to x
u'(x) = 34(4x+1)^2 and v'(x) = 2*cos(2x) using either substitution or simplification rules for both
Therefore, using product rule, dy/dx=[ 34(4x+1)^2 ] * [ sin(2x) ] + [ 2*cos(2x) ] * [ (4x+1)^3 ]
which simplifies to: dy/dx = 2(4x+1)^3*cos(2x) + 12(4x+1)^2