SOLUTION: Find the value of k that makes the line through (-4,k) and (-1, 2k) have a y-intercept of -7.

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: Find the value of k that makes the line through (-4,k) and (-1, 2k) have a y-intercept of -7.      Log On


   

Question 1150511: Find the value of k that makes the line through (-4,k) and (-1, 2k) have a y-intercept of -7.
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

the equation of the line:
y=mx%2Bb where m is a slope and b is y-intercept
given:
the line passes through (-4,k) and (-1, 2k)
and have a y-intercept of b=-7
use given points to find a slope m
m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29
m=%282k-k%29%2F%28-1-%28-4%29%29
m=k%2F%28-1%2B4%29
m=k%2F3
so far, your line is: y=%28k%2F3%29x-7
use one point and calculate k
k=%28k%2F3%29%28-4%29-7
k=-%284k%2F3%29-7....both sides multiply by 3
3k=-4k-21
3k%2B4k=-21
7k=-21
k=-21%2F7
k=-3
then, a slope is m=k%2F3=-3%2F3=-1
so, your equation is: y=-x-7
and points are: (-4,-3) and (-1, -6)