1.6 Lines
y x
L y x
Draw a graph of a line passing through the point (1,4) and having a slope -3/2.
(1, 4) -3 (3, 1) 2
Vertical Line
Graph the equation : x = 2
y x = 2 x
( ) Point-Slope Equation An equation of a nonvertical line of slope x y 1 , m that passes through the point is
(0, 3) (1, 1)
Equation of a Horizontal Line A horizontal line is given by an equation of the form y=b Where b is the y-intercept.
Find the equation and sketch a graph of a horizontal line passing through (1,4).
y y = 4 x
Slope-Intercept form of an Equation of a Line An equation of a line L with slope m and y-intercept b is y=mx+b
Th equation of a line L is in general form when it is written: Where A, B, and C are three real numbers and A and B are not both 0.
Criterion for Parallel Lines Two nonvertical lines are parallel if and only if their slopes are equal and they have different y-intercepts.
Two lines are said to be perpendicular if they intersect at a right (90o) angle.
Criterion for Perpendicular Lines Two nonvertical lines are perpendicular if and only if the product of their slopes is -1. The corresponding slopes m1 and m2 have the following relationship: