SLOPE

I'm back.  After taking some time to teach high school in the city of Pittsburgh, I'm returning to the Bohemian life of an itinerant SAT Tutor.

First rambling:

On every SAT is a question from Algebra I ~ SLOPE!

You remember; Slope = [Rise]/[Run]  and Slope Intercept Form is y = mx + b; where x and y are points on the line, m is the slope, and b is the where the line goes through the y-axis or "y-intercept."

Slope is from a line on the X-Y Plane.  It is also called a "Linear Function" but that is a lesson for another day.

Things to know:
1. A line through the origin; aka "Direct Variation."  Since the line goes through the origin (0,0), the y-intercept = 0. Sometimes they like to write it as y = kx where k is the constant of variation ~ but it is still the slope.
2. Parallel lines have same slope.  y = 3x - 5 is parallel to y = 3x + 2.5
3. Perpendicular lines are lines at right angles and have slopes that are "Opposite Reciprocal"  y = 2x + 1 is perpendicular to y = -(1/2)x + 1