Factor the following:
9 z^2+42 z+49
Factor the quadratic 9 z^2+42 z+49. The coefficient of z^2 is 9 and the constant term is 49. The product of 9 and 49 is 441. The factors of 441 which sum to 42 are 21 and 21. So 9 z^2+42 z+49 = 9 z^2+21 z+21 z+49 = 7 (3 z+7)+3 z (3 z+7):
7 (3 z+7)+3 z (3 z+7)
Factor 3 z+7 from 7 (3 z+7)+3 z (3 z+7):
(3 z+7) (3 z+7)
(3 z+7) (3 z+7) = (3 z+7)^2:
Answer: | (3z+7)^2
