Respuesta :

Answer:

Step-by-step explanation:

3(x+8)²-20=28

3(x+8)²=28+20

divide by 3

(x+8)²=48/3=16

x+8=±4

either x+8=4

x=4-8=-4

x=-4

or x+8=-4

x=-4-8=-12

x=-12