Question

Write the equation passing through the points (-9, 6 ) and (1, -5). The worksheet has multiple choice, so I know y intercept is either 39/10 or -39/10.

I have -11/10x plus b
then -11 (1) is -11
10(1) is 10

Then -5 plus 11/10
I change -5 to -15/10 but I'm getting -26/10.

What am I doing wrong?

Answer 1

Given P1(-9, 6) and P2(1, -5)
If the line is not vertical, the line through the two points has a slope of
m=(y2-y1)/(x2-x1)
=(-5-6)/(1-(-9)
=-11/10
This should eliminate some of the choices.
To find the intercept, you can use
(y-y1)=m(x-x1)
y=-(11/10)(x-(-9)+6
=-(11/10)x - 39/10
confirming one of your two options.