Question

How do you factor `5a^2 + 10ab - 15b^2`?

Answer 1

`y = 5(a^2 + 2ab - 3b^2)`

`= 5(a - b)(a + 3b)`

Check: y = 5(a^2 + 3ab - ab - 5b) . OK

Answer 2

To factor `5a^2+10ab-15b^2`
first extract the obvious common constant factor
then look for factors of the simplified variable term

`5a^2+10ab-15b^2`
`= 5(a^2+2ab-3b^2)`

`=5(a+3b)(a-b)`