Question:
Factor 4x2 - 12x + 9
Answer:
This is a perfect square trinomial. The square root of the first term is 2x or -2x. The square root of the last term is 3 or -3. Their product is plus or minus 6x. Double that is the middle term: -12x.
(2x - 3)2
Check it by multiplying it out, and you'll see it's right. Is it the only answer? Actually, no.
(-2x + 3)2
Would be another solution. Do you see that -2x+3 is the negative of 2x-3?