Originally Posted by Knox

You made a mistake when you subbed it into y=mx+b. You used the y value for b; the value of b should be the y-intercept value.

Here's the correct equation with explanations:

(-6,9) and (-11,-4)

First you find the slope between the two points:

m=delta y/delta x
m = (-4-9)/(-11-(-6))
m = -13/-5
m = 13/5

Then, since you have the slope and you also have two usable points that the line goes through, you sub it into this formula:

y=m(x-p)+q
Where m is the slope, y and x are left as they are, p is the x value of one point (TIMES -1, so it's sign will be opposite of what the x value is for the graph), and q is the y value of the same point.

y=m(x-p)+q
y=13/5(x+6)+9
y=13/5x+78/5+45/5
y=13/5x+123/5
y=2.6x+24.6

So, the equation of the line that contains the points (-6,9) and (-11,-4) is y=2.6x+24.6.