Question

Solve this quadratic equation by completing the square.
x2 + 6x = 18

Answer 1

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

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