document.write( "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 \n" ); document.write( "

Algebra.Com's Answer #632516 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
Parallel means it has the same slope,
\n" ); document.write( " $\"2x-7y=3\"$
\n" ); document.write( " $\"7y=2x-3\"$
\n" ); document.write( " $\"y=%282%2F7%29x-3\"$
\n" ); document.write( "So then,
\n" ); document.write( " $\"Ax%2BBy=7\"$
\n" ); document.write( " $\"-By=Ax-7\"$
\n" ); document.write( " $\"y=-%28A%2FB%29x-7\"$
\n" ); document.write( "and
\n" ); document.write( " $\"-%28A%2FB%29=2%2F7\"$
\n" ); document.write( " $\"7A=-2B\"$
\n" ); document.write( " $\"2B=-7A\"$
\n" ); document.write( "You also can use the point,
\n" ); document.write( " $\"A%282%29%2BB%281%29=7\"$
\n" ); document.write( " $\"2A%2BB=7\"$
\n" ); document.write( "Multiply both sides by 2,
\n" ); document.write( " $\"4A%2B2B=14\"$
\n" ); document.write( "Substitute from the first equation,
\n" ); document.write( " $\"4A-7A=14\"$
\n" ); document.write( " $\"-3A=14\"$
\n" ); document.write( " $\"A=-14%2F3\"$
\n" ); document.write( "Then,
\n" ); document.write( " $\"2B=-7%28-14%2F3%29\"$
\n" ); document.write( " $\"B=49%2F3\"$
\n" ); document.write( "So then,
\n" ); document.write( " $\"B-A=49%2F3-%28-14%2F3%29\"$
\n" ); document.write( " $\"B-A=63%2F3\"$
\n" ); document.write( " $\"B-A=21\"$
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