Question

Write an equation in slope-intercept form for the line that passes through (3,5) and (-2,1).

y2-y1/x2-x1
1-5/-2-3
-4/-5= slope

y=mx+b
y=-4/-5(3)+b
-2=2.4+b
-4.4= y-intercept

y= -4/-5x+4.4 (answer)

Answer 1

Rewrite the slope as m = 4/5. -4/-5 is the same thing but looks awkward.

y = (4/5) x + b
5 = [(4/5)*3] + b
5 = 12/5 + b
b = 13/5
y = (4/5)x + 13/5

Answer 2

Ok, we lmow that the slope is 4/5.
y=mx+b
y=4/5(3)+b
-2=2.4+b
subtract 2.4 from both sides
-4.4 which is how I got the y-intercept
y= 4/5x+4.4

13/5 = 2.6 not 4.4

Answer 3

In solving for b, you took the x-value from one point (x=3) and, for y, you used the x value from the other point (x=-2) instead of y. You should have used y=5, as I did in my derivation. You have to use the x and y values of one known point to get the line to pass though that point.