Take the square root of each side of the equation to set up the solution for

Remove the perfect root factor under the radical to solve for .

Rewrite as .

Pull terms out from under the radical, assuming positive real numbers.

First, use the positive value of the to find the first solution.

Move all terms not containing to the right side of the equation.

Add to both sides of the equation.

Add and .

Next, use the negative value of the to find the second solution.

Move all terms not containing to the right side of the equation.

Add to both sides of the equation.

Add and .

The complete solution is the result of both the positive and negative portions of the solution.

Solve Using the Square Root Property (y-20)^2=81