1) The square root method implies that we must rewrite the quadratic equation as (ax +b)²=c
2) Examining x²+8x+16=25.
x²+8x+16=25 Note that this is a perfect square trinomial
(x+4)²=25 After rewriting it we can take the square root
√(x+4)²=√25
x+4 = 5
x=1
(x+4) = -5
x+4 =-5
x=-5-4
x=-9
x=-9
S ={-9,1}