Respuesta :

Answer: x = 4

Step-by-step explanation:

This is easy, just use the Area formula as A=lw and substitute the values.

A=x2+7x+12

L=(x+4)

W= x

A=L(w)

x2+7x+12 = (x+4)x

x2+7x+12= x2+4x

x2-x2+7x-4x=-12

3x=-12

x=-4