Question

How do you factor the expression `-5a^2 - ab + 6b^2`?

Answer 1

`(5a+6b)(b-a)`

Explanation:

If you multiply the coefficients of `a^2 and b^2` you get `-30`. You need factors of `-30` which differ by `-1`, namely `-6` and 5 which allows you to rewrite the equation as:

`-5a^2-6ab+5ab+6b^2`

You can factorize both pairs separately to give you:

`-a(5a+6b) + b(5a+6b)` which you collect as the answer above