Product Rule For Differentiation
Let u and v be differentiable functions of x. Then the product function
y = u(x) v(x) is differentiable.
y′ = u(x) v′(x) + v(x) u′(x)
This rule can be remembered as:
Derivative of the product of two functions = (1st function) (derivative of 2nd function) + (2nd function) (derivative of 1st function)