SOLUTION: The line that passes through the points (3a,4),(-1,2) is parallel to the graph of -4x+2y=6.Find the value of a.

Algebra ->  Linear-equations -> SOLUTION: The line that passes through the points (3a,4),(-1,2) is parallel to the graph of -4x+2y=6.Find the value of a.      Log On


   

Question 843830: The line that passes through the points (3a,4),(-1,2) is parallel to the graph of -4x+2y=6.Find the value of a.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
That means the slopes of the two lines are equal. Use the formula for slope with your given points, one of them containing a variable, and solve for the variable.

This -4x+2y=6 is really -2x+y=3.
The slope is 2.
(You can also get slope from form Ax+By=C by making m=-%28A%2FB%29. )

Now to use slope formula:
m=2=%282-4%29%2F%28-1-3a%29
2=%28-2%29%2F%28%28-1%29%281%2B3a%29%29
Solve for a.


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You can also find the equation for the line:
You already KNOW the needed slope is 2, and you have one known given point.
USE POINT SLOPE FORMULA but still you just need any equation form, and the slope and one known point.
y-v=m%28x-u%29 for some known (u,v).
y-2=2%28x-%28-1%29%29 which simply uses the known slope and known point (-1,2).
y-2=2%28x%2B1%29
y=2x%2B2%2B2
highlight%28y=2x%2B4%29