Respuesta :

Let's factor the trinomial.
x^2+19x+84.
Find two numbers that add to 19 and multiply to 84.
They happen to be 7 and 12.
x^2+7x+12x+84
x(x+7)+12(x+7)
Gather like terms.
(x+7)(x+12)
Therefore, the answer is D.