Question

If y = 2x^3 + 4x and dx/dt = 2, find dy/dt when x = 4.

Answer 1

dy/dx = 6x² +4 . . . . . using the power rule

dy/dt = (dy/dx)×(dx/dt) = (6(4²) +4)×2

dy/dt = 200 . . . at x=4