The power rule is a quick means of finding the derivative of a function. To apply the power rule, take the exponent and make it the new coefficient of the derivative. Now decrement the exponent by one. The resulting function is the derivative of the original function.

f(x) = x2
f1 (x) = 2x2-1
f1 (x) = 2x1
f1 (x) = 2x

If the variable has a coefficient, the power rule is applied to the exponent and variable in the above manner and then multiplied by that coefficient, as follows:

f(x) = 4x3
f1 (x) = 4 * (3x2)
f1 (x) = 12x2