# How do I use the limit definition of derivative to find #f'(x)# for #f(x)=5x-9x^2# ?

##### 1 Answer

Sep 19, 2014

Let us find

Start with

Let us find

Let us find the difference quotient.

by plugging in the expression we found above,

by cancelling out

by factoring

by cancelling out

Now, we can find