math
posted by Bob .
factor the polynomial:
x^2 + 6x + 9

Try a perfect square:
(x+a)²
=x²+2ax+a² 
x^2+6x+9
Product of the coefficients of the 1st and last terms: +9 (1x9)
Sum: +6 (middle term is always the sum)
List all the factors of 9 and determine which pair would give you a product of +9 and a sum of +6:
1,9
3,3 ✓
your answer will be (x+3)^2 or (x+3)(x+3)
Check: F.O.I.L. (x+3)(x+3)
x^2+3x+3x+9
x^2+6x+9