Question

Why would the answer when factoring the polynomial 9x^2 − 324y^2
not be (3x-18y)(3x+18y) but instead be 9(x-6y)(x+6y) ?

Answer 1

because you can factor the GCF 9 from the original polynomial


or


you can factor two copies of 3 from each group (in parenthesis) to get 3*3 = 9


Either way, the complete factorization will be 9(x-6y)(x+6y)

Answer 2

by the second method, I mean

(3x-18y)(3x+18y)


3(x-6y)3(x+6y)


3*3(x-6y)(x+6y)


9(x-6y)(x+6y)

Answer 3

how did you get the 6?

Answer 4

(3x-18y) = 3(x-6y)


and


(3x+18y) = 3(x+6y)