# How do you factor completely #ax^2-9a+bx^2-9b#?

##### 1 Answer

Nov 13, 2015

#### Explanation:

Look for 'repeats' and 'play' to see if they can be used to your advantage!

Write as:

Then we have

Not finished yet! Remember that

I have just spotted that we have this situation in the previous line of the solution.

Rewrite (1) as:

Expanding (3) gives: