Question 327900
The problem : x^2 + 2x = 8, can be solved by completing the square as follows:

x^2 + 2x = 8

Next we want to take 1/2 of the coefficient, 2 which is 1 and then square 1.

1 squared is 1, so we add 1 to both sides:

x^2 + 2x + 1 = 8 + 1

Next we simplify:

x^2 + 2x + 1 = 9

Remember: x^2 + 2x + 1 is equivalent to (x + 1)^2. If we were to FOIL out
(x +1)^2 we would get: x^2 + 2x + 1.
In order to solve this equation, we will use (x + 1)^2 on the left hand side.

(x + 1)^2 = 9

To solve for x, we must undo the squaring operation on the left hand side. We do this by taking the square root of both sides:

sqrt(x + 1) ^2 = + or - sqrt (9)

Yielding: x + 1 = + or - 3

Next we evaluate:

x + 1 = 3 and x + 1 = -3

The first equation x + 1 = 3, x is 2.

The second equation x + 1 = -3, x = -4