SOLUTION: slope= -1/3; passing through (9,-1) Write an equation in point-slope form and slope-intercept form.

Algebra ->  Rational-functions -> SOLUTION: slope= -1/3; passing through (9,-1) Write an equation in point-slope form and slope-intercept form.      Log On


   

Question 1010039: slope= -1/3; passing through (9,-1)
Write an equation in point-slope form and slope-intercept form.
Found 2 solutions by josgarithmetic, MathLover1:
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
Two points, (x,y) and (p,w) will have a slope m=%28w-y%29%2F%28p-x%29.

m%28p-x%29=w-y
%28-1%29m%28p-x%29=%28-1%29%28w-y%29
m%28x-p%29=y-w
highlight_green%28y-w=m%28x-p%29%29--------point slope form equation of a line for known slope m and known point (p,w).

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
given:
slope=+-1%2F3;
passing through (9,-1)=(x%5B1%5D,y%5B1%5D)
an equation in point-slope form is:
y-y%5B1%5D+=+m%28x-x%5B1%5D%29
y+-%28-1%29+=+-%281%2F3%29%28x-9%29
y+%2B1+=+-%281%2F3%29%28x+-9%29

and slope-intercept form
y=mx%2Bb....use given slope and point to find y-intercept b
-1=-%281%2F3%29%2A9%2Bb
-1=-%281%2Fcross%283%291%29%2Across%289%293%2Bb
-1=-3%2Bb
-1%2B3=b
b=2

so, your line is:
y+%2B1+=+-%281%2F3%29%28x+-9%29
or
y=-%281%2F3%29x%2B2