Parallel/Perpendicular Lines
y = x + 4 y = 2x + 5
r + s = -6 r - s = -10
x = 4y 2x + 3y = 22
What is the equation for slope?
rise over run; y2 - y1 _____ x2 - x1
y = 3x - 2 y = -x - 2
8a + 5b = 9 2a - 5b = -4
y = x - 2 3x - y = 16
Do parallel lines ever intersect?
No
y = -3 x = 5
2x + 3y = 6 3x + 5y = 15
The equations for slope-intercept form, point-slope form, and standard form
y = mx + b
y - y1 = m(x - x1)
Ax + By = C
y = (1/3)x - 3 2x - y = 8
2a - 4b = 12 -8a + 16b = -48
3s - 2t = 4 t = 2s - 1
Perpendicular lines have these slopes
opposite reciprocals
y - 3x = 3 y = 3x - 2
This m-value would make a line perpendicular to y = -4x + 2.
m =
1/4