document.write( "Question 159177: solve the following system of equations by substitution... please\r
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\n" ); document.write( "\n" ); document.write( " $\"-x%2B3y=11\"$
\n" ); document.write( " $\"4x-y=-11\"$ \n" ); document.write( "

Algebra.Com's Answer #117300 by nerdybill(7384) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"-x%2B3y=11\"$ equation 1
\n" ); document.write( " $\"4x-y=-11\"$ equation 2
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\n" ); document.write( "Solve equation 1 for x:
\n" ); document.write( " $\"-x%2B3y=11\"$
\n" ); document.write( " $\"3y=x%2B11\"$
\n" ); document.write( " $\"3y-11=x\"$
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\n" ); document.write( "Substitute the above into equation 2 and solve for y:
\n" ); document.write( " $\"4x-y=-11\"$
\n" ); document.write( " $\"4%283y-11%29-y=-11\"$
\n" ); document.write( " $\"12y-44-y=-11\"$
\n" ); document.write( " $\"11y=33\"$
\n" ); document.write( " $\"y=3\"$
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\n" ); document.write( "Finally, substitute the above back into equation 1 and solve for x:
\n" ); document.write( " $\"-x%2B3y=11\"$
\n" ); document.write( " $\"-x%2B3%283%29=11\"$
\n" ); document.write( " $\"-x%2B9=11\"$
\n" ); document.write( " $\"9=x%2B11\"$
\n" ); document.write( " $\"-2=x\"$
\n" ); document.write( ".
\n" ); document.write( "Solution: x = -2 and y = 3
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