Question 1015977
Parallel means it has the same slope,
{{{2x-7y=3}}}
{{{7y=2x-3}}}
{{{y=(2/7)x-3}}}
So then,
{{{Ax+By=7}}}
{{{-By=Ax-7}}}
{{{y=-(A/B)x-7}}}
and
{{{-(A/B)=2/7}}}
{{{7A=-2B}}}
{{{2B=-7A}}}
You also can use the point,
{{{A(2)+B(1)=7}}}
{{{2A+B=7}}}
Multiply both sides by 2,
{{{4A+2B=14}}}
Substitute from the first equation,
{{{4A-7A=14}}}
{{{-3A=14}}}
{{{A=-14/3}}}
Then,
{{{2B=-7(-14/3)}}}
{{{B=49/3}}}
So then,
{{{B-A=49/3-(-14/3)}}}
{{{B-A=63/3}}}
{{{B-A=21}}}
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