Relationships Among Linear Functions

Graphing systems of two linear equations is another effective approach to solving them. Practice arranging linear equations into y = mx + b form and graphing them in the coordinate plane.

If the slopes of line ℓ and line k are each defined (that is, if neither line is a vertical line), then

• Line ℓ and line k are parallel if and only if they have the same slope. 

• Line ℓ and line k are perpendicular if and only if the product of their slopes is −1.