SOLUTION: The ordered pairs are for a direct variation. Find the missing value. I know that the direct variation form is y=kx but I'm not sure how to use it to find the missing value of the

Algebra ->  Equations -> SOLUTION: The ordered pairs are for a direct variation. Find the missing value. I know that the direct variation form is y=kx but I'm not sure how to use it to find the missing value of the       Log On


   

Question 281609: The ordered pairs are for a direct variation. Find the missing value. I know that the direct variation form is y=kx but I'm not sure how to use it to find the missing value of the ordered pair.
(-2,8) and (x,12)
Found 2 solutions by jim_thompson5910, richwmiller:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Since each ordered pair is of the form (x,y), this means that the point (-2,8) gives the values x=-2 and y=8


So plug these values into y=kx to get 8=k%28-2%29. Now divide both sides by -2 to get k=-4. So the equation is y=-4x. Now the point (x,12) means that y=12. So plug this into y=-4x to get 12=-4x. Finally, divide both sides by -4 to isolate 'x' to get x=-3


So the second point is (-3,12). Let me know if this helps.

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
y=kx
plug in the first ordered pair (-2,8) to find k
8=k*(-2)
-4=k
y=-4x
now plug in the y of (x,12) to find x
12=-4x
-3=x
(-3,12)