Subtract from both sides of the equation.

Take the square root of both sides of the equation to eliminate the exponent on the left side.

Simplify the right side of the equation.

Rewrite as .

Since both terms are perfect squares, factor using the difference of squares formula, where and .

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

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

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

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

To rewrite as a function of , write the equation so that is by itself on one side of the equal sign and an expression involving only is on the other side.

Write as a Function of x x^2+y^2=169