15 Feb 2018

School

Department

Course

Professor

Lecture #4 - Slope/Domain and Range

Slope :

m = slope

m = (y2 - y1) / (x2-x1) OR m = change in y / change in x

Slope is most commonly referred to as “rise over run”

Different forms of lines:

Point slope form: y - y0 = m (x - x0)

General form: ax + by + c = 0

Slope intercept form: y = mx + b

*General form includes all possible lines, while the other two do not include vertical lines, this

is what makes the general form useful. Point slope form is useful for tangent lines.

Slope of perpendicular lines is always the negative reciprocal of the original lines slope.

Ex.

A line has the equation y = 3/2x + 5. Find the slope of the perpendicular line.

Slope of original = 3/2.

Therefore the slope of the perpendicular line is the negative reciprocal of 3/2 which is -2/3.

Answer = -2/3

Ex.

Find an equation for the line through (1,3) perpendicular to the line 2x - 3y = 5.

1. Find slope of given line