July 20, 2011

The Power Rule

This is a calculus lesson based on a question:
 Would you be able to explain how to derive a square root? 
The power rule is used to find the derivative of (or "differentiate" or "find the instantaneous rate of change of") an algebraic expression of the form x to a numerical power, or xn.

The derivative of a function ƒ(x) = xn is ƒ'(x) = n * xn-1. If it is easier to remember think of it as dragging the exponent down (to multiply the x by) and then subtracting one in the exponent.

Here are some examples to clarify:



One special case is the square root function. What we must remember about this function is that √(x) is the same as x1/2.

1 comment:

  1. I'm sorry, there is a typo in the last example. That should have been ƒ'(x) (the derivative of ƒ(x)) in the second step. In the first step I simplified ƒ(x), then in the second step I actually took the derivative.

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