Solve:(x+5)^2 =16
(x+5)^2 =16
x^2 + 10x + 25 - 16 = 0
x^2 + 10x + 9 = 0
(x+9)(x+1) = 0
x + 9 = 0
x = -9
x +1 = 0
x = -1
answer: x=-1 and x = -9
Solve: a^2 +12a + 36 = 225
a^2 +12a + 36 = 225
a^2 +12a + 36 - 225 = 0
a^2 +12a - 189 = 0
(a-9)(a+21) = 0
a - 9 = 0
a = 9
a + 21 = 0
a = -21
answer: a = -21 and a = 9