Solve (2x+8)^(1/2)=x

(2x + 8)^(1/2) = x
2x + 8 = x^2
x^2 - 2x - 8 = 0
x = (2 +/- sqrt(4 + 32)) / 2
x = (2 +/- 6) / 2
x = 1 +/- 3
x = -2 , 4

Test the answers in the original equation. If non-principal roots can be used, then both answers are valid. If non-principal roots cannot be used, then only one answer will work.

(2x + 8)^1/2

x = -4