Question

Factor completely 9x2 + 42x + 49.

A. (3x + 7)(3x − 7)
B. (9x − 7)(9x − 7)
C. (3x + 7)(3x + 7)
D. (9x + 7)(9x + 7)

Answer 1

factor each term to see a GCF maybe

`9x^2=3*3*x*x`

`42x=2*3*7*x`

`49=7*7`
no gcf

ok, hum
well, we see the first term might be √9 or 3 and the last must be √49 or 7

lets try (3x+7)(3x+7)

`9x^2+21x+21x+49=9x^2+42x+49`
works

answer is (3x+7)(3x+7)