Question

Find the slope of the line that contains the two points (3,2) and (1,-4).

m = - 3
m = - 1/3 <-- ?
m = 3
m = 1/3

Find the slope of the line that contains the points (-2, 4) and (-4, 6).

m = -1
m = 1 <--
m = - 1/3
m = 1/3


Find the equation of the line that passes through the points (7,4) and (-5,-2)?

y=1/2x-1/2
y=-1/2x-1/2
y=-1/2x+1/2<--
y=1/2x+1/2

Find the equation of the line that passes through the points (1,4) and (2,-8).

y = -3x + 9
y = 6x + 5
y = -12x + 16
y = 12x - 8 <---

Answer 1

1. (3,2), (1,-4)
m = (y2-y1)/(x2-x1) = (-4-2)/(1-3) = -6/-2 = 3.

2. (-2,4), (-4,6).
m = (6-4)/(-4-(-2)) = 2/-2 = -1.

3. (7,4), (-5,-2).
m = (-2-4)/(-5-7) = -6/-12 = 1/2.
Y = mx + b
4 = (1/2)7 + b, b = 1/2.
Y = (1/2)x + 1/2.

4. (1,4), (2,-8).
m = (-8-4)/(2-1) = -12,
Y = mx + b.
4 = -12*1 + b, b = 16.
Y = -12x + 16.