Question

(x+2)^2+13(x+2)+36

Answer 1

Substitute t = x+ 2.
It will be a quadratic equation in t.
Solve for t.
Replace t by x + 2 and solve for x.

Answer 2

(x+2)^2+13(x+2)+36 = 0
Let t = x + 2
t^2 + 13t + 36 = 0
t^2 + 9t + 4t + 36 = 0
t(t+9) + 4(t+9) = 0
(t+4)(t+9) = 0
t = -4 or -9
Put back x + 2 in the place of t
x + 2 = - 4 or x + 2 = -9
x = -6 or x = -11

Answer 3

If the question was to FACTOR (x+2)^2+13(x+2)+36 instead of solving for x then the answer would be: (x + 6)(x + 11). Similar procedure as before:
(x+2)^2+13(x+2)+36
Let t = x + 2
t^2 + 13t + 36
t^2 + 9t + 4t + 36
t(t+9) + 4(t+9)
(t+4)(t+9)
Put back x + 2 in the place of t
(x+2+4)(x+2+9)
(x+6)(x+11)