X2+2x+8=0 solve by completing the square

x = i sqrt (7) - 1 or x = - i sqrt (7) - 1

Step-by-step explanation:

Solve for x:

x^2 + 2 x + 8 = 0

Subtract 8 from both sides:

x^2 + 2 x = - 8

Add 1 to both sides:

x^2 + 2 x + 1 = - 7

Write the left hand side as a square:

(x + 1) ^2 = - 7

Take the square root of both sides:

x + 1 = i sqrt (7) or x + 1 = - i sqrt (7)

Subtract 1 from both sides:

x = i sqrt (7) - 1 or x + 1 = - i sqrt (7)

Subtract 1 from both sides:

Answer: x = i sqrt (7) - 1 or x = - i sqrt (7) - 1