Answer:
I assume you meant 12x^2 + 37x + 21
x = -7/3 & -3/4
Step-by-step explanation:
(12x^2 + 9x) + (28x + 21)
3x(4x +3) + 7(4x+3)
(3x+7) (4x+3)
(3x+7) --> 3x = -7 --> x = -7/3
(4x+3) --> 4x = -3 --> x = -3/4
