SOLUTION: `Find B - A if the graph of Ax + By = 7 passes through (2,1) and is parallel to the graph of 2x - 7y = 3

Algebra ->  Coordinate-system -> SOLUTION: `Find B - A if the graph of Ax + By = 7 passes through (2,1) and is parallel to the graph of 2x - 7y = 3      Log On


   

Question 1015977: `Find B - A if the graph of Ax + By = 7 passes through (2,1) and is parallel to the graph of 2x - 7y = 3
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Parallel means it has the same slope,
2x-7y=3
7y=2x-3
y=%282%2F7%29x-3
So then,
Ax%2BBy=7
-By=Ax-7
y=-%28A%2FB%29x-7
and
-%28A%2FB%29=2%2F7
7A=-2B
2B=-7A
You also can use the point,
A%282%29%2BB%281%29=7
2A%2BB=7
Multiply both sides by 2,
4A%2B2B=14
Substitute from the first equation,
4A-7A=14
-3A=14
A=-14%2F3
Then,
2B=-7%28-14%2F3%29
B=49%2F3
So then,
B-A=49%2F3-%28-14%2F3%29
B-A=63%2F3
B-A=21
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