Separate the constant term from the rest of the expression.
2(x - 3)^2 = 90
Divide 2 on both sides.
(x - 3)^2 = 45
Take the square root of both sides.
x - 3 = +- sqrt(45)
x - 3 = +- 3 * sqrt(5)
x = 3 * sqrt(5) + 3
x = -3 * sqrt(5) + 3
Hope this helps!
