document.write( "Question 162864: Solve by substitution or elimination:
\n" ); document.write( "2x-3y+z=14
\n" ); document.write( "4x+2y-5z=-3
\n" ); document.write( "x+y+2z=1
\n" ); document.write( "

Algebra.Com's Answer #120071 by elima(1433)\"\" \"About 
You can put this solution on YOUR website!
I'll use elimination to solve;
\n" ); document.write( "2x-3y+z=14
\n" ); document.write( "4x+2y-5z=-3
\n" ); document.write( "x+y+2z=1
\n" ); document.write( "==================
\n" ); document.write( "First add two equations together to eliminate a variable;
\n" ); document.write( "4x+2y-5z=-3 - multiply equation by 2 so you can eliminate the z;
\n" ); document.write( "x+y+2z=1 - multiply equation by 5 so you can eliminate the z;
\n" ); document.write( "=========================
\n" ); document.write( "2(4x+2y-5s=-3)
\n" ); document.write( "8x+4y-10z=-6
\n" ); document.write( "5(x+y+2z=1)
\n" ); document.write( "5x+5y+10z=5
\n" ); document.write( "===============
\n" ); document.write( "8x+4y-10z=-6
\n" ); document.write( "5x+5y+10z=5
\n" ); document.write( "-----------
\n" ); document.write( "13x+9y=-1
\n" ); document.write( "====================
\n" ); document.write( "Now choose two others to eliminate the z;
\n" ); document.write( "2x-3y+z=14 - multiply by -2
\n" ); document.write( "x+y+2z=1
\n" ); document.write( "=======================
\n" ); document.write( "-2(2x-3y+z=14)
\n" ); document.write( "-4x+6y-2z=-28
\n" ); document.write( "x+y+2z=1
\n" ); document.write( "------------
\n" ); document.write( "-3x+7y=-27
\n" ); document.write( "====================
\n" ); document.write( "Now add the two new equations together to eliminate another variable;
\n" ); document.write( "13x+9y=-1 - multiply by -7
\n" ); document.write( "-3x+y=-27 - multiply by 9
\n" ); document.write( "============================
\n" ); document.write( "-7(13x+9y=-1)
\n" ); document.write( "-91x-63y=-14
\n" ); document.write( "9(-3x+7y=-27)
\n" ); document.write( "-21x+63y=-243
\n" ); document.write( "=============================
\n" ); document.write( "-91x-63y=7
\n" ); document.write( "-27x+63y=-243
\n" ); document.write( "-------------
\n" ); document.write( "-118x=-236
\n" ); document.write( "x=2
\n" ); document.write( "=======================
\n" ); document.write( "Now that we have the x, let's plug it into one of the new equations and solve for y;
\n" ); document.write( "13(2)+9y=-1
\n" ); document.write( "26+9y=-1
\n" ); document.write( "9y=-27
\n" ); document.write( "y=-3
\n" ); document.write( "===========================
\n" ); document.write( "We have our x and y, let's plug them in and get the z;
\n" ); document.write( "x+y+2z=1
\n" ); document.write( "2+-3+2z=1
\n" ); document.write( "-1+2z=1
\n" ); document.write( "2z=2
\n" ); document.write( "z=1
\n" ); document.write( "=========================
\n" ); document.write( "check;
\n" ); document.write( "2x-3y+z=14
\n" ); document.write( "2(2)-3(-3)+1=14
\n" ); document.write( "4+9+1=14
\n" ); document.write( "14=14
\n" ); document.write( "check;
\n" ); document.write( "4x+2y-5z=-3
\n" ); document.write( "4(2)+2(-3)-5(1)=-3
\n" ); document.write( "8-6-5=-3
\n" ); document.write( "-3=-3
\n" ); document.write( ":)
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