Question

Find the equation of the line through point (5,1) and perpendicular to 5x−y=−3. Use a forward slash (i.e. "/") for fractions (e.g. 1/2 for 12).

Answer 1

y = -1/5x + 2

A line perpendicular to another line has an opposite reciprocal slope. What opposite means is that you flip the sign (from - to + or from + to -) and reciprocal means that you flip the numerator and denominator (so if line A is perpendicular to line B and line As slope is -3, line Bs slope would be 1/3).

First find the slope of 5x - y = -3
Add y to both sides
5x = y - 3
Add 3 to both sides
y = 5x + 3

So the slope of the line is 5. That means the slope of of the perpendicular line is -1/5.

Plug the slope of the perpendicular line and the point (5, 1) into point slope form to solve the equation

y - y1 = m(x - x1)
y - 1 = -1/5(x - 5)
y - 1 = -1/5x + 1
y = -1/5x + 2