Before you ask us a question, first check our FAQ and tags page to see if something similar has already been answered. If not, ask away! We can give you step by step explanations or any help at all in any aspect of maths you want.

**We're currently not looking for new admins!**

Administrative notes can be found here.

asks:

How would you factor: x^2-y^2+4y-4? My teacher got (x-y+2) (x+y-2). Thanks!

Let’s face it, factoring is an art, really. You might notice that y^2-4y+4 is a perfect square, namely (y-2)^2.

So then your original expression actually looks like x^2 - (y-2)^2, which is a difference of squares! So then you factor accordingly to end up with

(x - (y - 2))*(x + (y - 2)) = (x - y + 2)(x + y - x)

- H2

- say-carty likes this
- maths-help posted this