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 ->  Points-lines-and-rays -> 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 1015741: 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 josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!
Parallel to 2x-7y=3 means the wanted line must have the same slope.
-7y=-2x%2B3
y=%282%2F7%29x-3%2F7
NEED slope 2%2F7 but the needed equation is y=%282%2F7%29x%2Bb.

MUST contain (1,2).
%282%2F7%29%2A1%2Bb=2
b=2-2%2F7
b=14%2F7-2%2F7
b=12%2F7
-
y=%282%2F7%29x%2B12%2F7
-%282%2F7%29x%2By=12%2F7
-2x%2B7y=12--------but you want the constant term of the RIGHT member to be 7 because
the specified form was given as Ax+By=7.

%28-2x%2B7y%29%287%2F12%29=12%287%2F12%29
highlight%28highlight%28-%287%2F6%29x%2B%2849%2F12%29y=7%29%29

highlight%28system%28A=-7%2F6%2CB=49%2F12%29%29