Solve this quadratic equation by completing the square.

x2 + 6x = 18

x=3sqrt3-3; x=-3sqrt3-3

Step-by-step explanation:

solve for a, 2ax=6x; a=3:

x^2+6x+3^2=18+3^2

Simplify, 18+3^2=27:

x^2+6x+3^2=27

Complete square: (x+3) ^2=27

Two answers: x+3=sqrt27; x+3=-sqrt27

Therefore, x=3sqrt3-3; x=-3sqrt3-3