Solve using the quadratic formula x^2+4x-40=-8

Start by moving the 8 over to the other side:
x^2+4x-32=0

Then you can do a factor tree for -32 (what two numbers add to 4 and multiply to -32):
You should get 8 & -4 as your two numbers

Then plug it in to the equation:
(x+8)(x-4)=0

Set them both equal to zero:
x+8=0 x-4=0
x=-8 x=4