To find the x intercepts of a given equation, simply substitute in y=0
x^2+4x-32=0
Solve via sum and product (what two numbers add up to +4 and what two numbers multiply to give -32)
x^2+8x-4x-32=0
x(x+8)-4(x+8)=0
(x-4)(x+8)=0
(x-4)=0 and (x+8)=0
So, the two x intercepts are 4 and -8, which is option b
