Math 80 Unit 3.1 – 3.4
SUPPLEMENT
LINEAR EQUATIONS
Slope of a linear equation
Slope = m =
Forms of equations of lines
Standard (General) Form
Slope-Intercept Form
Point-Slope Form
.To find an equation of a line use either Slope-Intercept or Point-Slope
1) If given the slope and the y-intercept use Slope-Intercept
(plug in slope=m and y-intercept=b)
2) If given a point and the slope use Point-Slope
(plug in the point (
) and the slope=m)
3) If given two points use Point-Slope
(first find slope using the two points and slope formula,
then use either point and the slope in Point-Slope)
To find x-intercept, let y = 0, then solve for x
To find y-intercept, let x = 0, then solve for y
The graph of y = b is a horizontal line with y-intercept b
The graph of x = a is a vertical line with x-intercept a
Slope of a horizontal line is 0
Slope of a vertical line is undefined
A line with a positive slope slants up to the right
A line with a negative slope slants down to the right
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