document.write( "Question 766025: Hello can you help me with this problem? It says you have to use the subsitution method to solve a system of equations that has three variables.\r
\n" ); document.write( "\n" ); document.write( "6x-4y+5z=31
\n" ); document.write( "5x+2y+2z=13
\n" ); document.write( "x+y+z=2\r
\n" ); document.write( "\n" ); document.write( "x=?
\n" ); document.write( "y=?
\n" ); document.write( "z=?
\n" ); document.write( "

Algebra.Com's Answer #466639 by rothauserc(4718)\"\" \"About 
You can put this solution on YOUR website!
6x-4y+5z=31
\n" ); document.write( "5x+2y+2z=13
\n" ); document.write( "x+y+z=2
\n" ); document.write( "========================================================================
\n" ); document.write( "x+y+z=2
\n" ); document.write( "solve for z
\n" ); document.write( "z=2-x-y
\n" ); document.write( "==================================================================
\n" ); document.write( "substitute for z in second equation
\n" ); document.write( "5x+2y+2*(2-x-y)=13
\n" ); document.write( "5x+2y+4-2x-2y=13
\n" ); document.write( "3x=9
\n" ); document.write( "x=3
\n" ); document.write( "====================================
\n" ); document.write( "substitute for z and x in equation 1
\n" ); document.write( "6*3 -4y +5*(2-3-y)=31
\n" ); document.write( "18 -4y +10 -15 -5y = 31
\n" ); document.write( "-9y +13 = 31
\n" ); document.write( "-9y = 18
\n" ); document.write( "y = -2
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\n" ); document.write( "substitute x=3 and y=-2 into third equation
\n" ); document.write( "3-2+z=2
\n" ); document.write( "1+z=2
\n" ); document.write( "z=1
\n" ); document.write( "=============================================
\n" ); document.write( "check values in first, second and third equations
\n" ); document.write( "6*3 -4*(-2) +5*1 = 31
\n" ); document.write( "18 +8 +5 = 31
\n" ); document.write( "31 = 31 equation 1 checks
\n" ); document.write( "++++++++++++++++++++++++++++++++++++++++
\n" ); document.write( "5*3 +2*(-2) + 2*1 = 13
\n" ); document.write( "15 -4 +2 = 13
\n" ); document.write( "13 = 13 equation 2 checks
\n" ); document.write( "+++++++++++++++++++++++++++++++++++++++++
\n" ); document.write( "3 -2 + 1 = 2
\n" ); document.write( "2 = 2 equation 3 checks
\n" ); document.write( "===============================================
\n" ); document.write( "x=3, y=-2, z=1\r
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