1. Equations of
Lines

2. Equations to Remember Slope-Intercept Form
Use this form to graph equations, since m is the slope and b is the y-intercept.
Point-Slope Form
Use this form when you know a point on the line and the slope
Also can use this version if you have two points on the line because you can first find the slope using the slope formula and then use one of the points and the slope in this equation.
Standard Form
Useful when solving two linear equations.

3. Parallel and Perpendicular Lines
Parallel lines have the same slopes.
If you need the slope of a line parallel to a given line, simply find the slope of the given line and the slope you want for a parallel line will be identical.
Perpendicular lines have negative reciprocal slopes.
If you need the slope of a line perpendicular to a given line, simply find the slope of the given line, flip it over and make it the opposite sign.
When perpendicular lines intersect, they form a right angle.

4. The Four Types of Slopes

5. If you don’t have the slope but have two points, then use the slope formula to find the slope.