I really need help factoring these special Trinomials.

This question really puzzled me. I thought I had it correct, but when I checked the answer at the back of the book, I was wrong, and so I would like to know what was it that I had done wrong.

This was the question:

x^2-4x+4

This is how I solved it:

x^2-4x+4
x^2-2x-2x+4
x(x-2)-2(x+2)
(x-2)(x+2)

- I could not get any further than this. I thought that this would be correct, but the actual answer is
(x-2)^2

How did they get that?
If there is an easier way to solve this, then can you please show me how. Cause solving things like I have above is difficult.

1 answer

Your error is in this line of yours

x(x-2)-2(x+2)
notice when you multiply it back out you don't get your original, and you don't have a "common" factor.

should have been
x(x-2)-2(x-2) to get back your x^2 - 4x + 4
= (x-2)(x-2)
= (x-2)^2