Solve the quadratic equation using the square root property

Solve the quadratic equation using the square root property. If possible, simplify radicals or rationalize denominators

y² - 14y + 49 = 18

Solution

y^2 - 14y + 49 = 18
y^2 - 2*y*7 + 7^2 = 18
(y-7)^2 = 18

y-7 = -sqrt(18) and y-7 = sqrt(18)
y-7 = -3*sqrt(2) and y-7 = 3*sqrt(2)

so,
y = 7 - 3*sqrt(2) and
y = 7 + 3*sqrt(2)