# Differentiating Quadratics (and other polynomials)

Author:
jgregg

## The definition of a derivative of a function

In the previous activity, you may have noticed the following formula. gradient function The first part of this is read as the limit as h tends to 0, it means we are interested in what happens as h approaches zero. The next part asks us to evaluate a function at different points and divide by h. If we perform this calculation for the function let us see what happens So If we divide this expression by h we get But remember I am interested in what happens as , so this evaluates to This is the gradient function for We can perform the same calculations for Dividing by h gives and since the gradient function is As an exercise, you could try to perform the same process for different quadratic, cubics and other polynomials. You may even like to try some other functions.