Change the given equation to slope-intercept to get . When you multiply the slopes of perpendicular lines, you get -1. -1 divided by is . The slope of the new line is then . The perpendicular line passes through (5, 5) so you can have the equation. Simplifying gets . So now the final equation for the perpendicular line is
If it's a perfect square, then it's easy. However, if it's not a perfect square, use the square root button on your calculator. IF you happen to know calculus then you could use Newton's Method....but I'm thinking you're not there yet. So stick with the calculator.