document.write( "Question 1012903: Solve the system of equations
\n" ); document.write( "3x+4y+z=7
\n" ); document.write( " 2y+z=3
\n" ); document.write( "-5x+3y+8z=-31 \n" ); document.write( "
Algebra.Com's Answer #629036 by Alan3354(69443)\"\" \"About 
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3x+4y+z=7
\n" ); document.write( " 2y+z=3 --> z = -2y+3
\n" ); document.write( "-5x+3y+8z=-31
\n" ); document.write( "-------------
\n" ); document.write( "Sub for z in the 1st & 3rd equations.
\n" ); document.write( "3x+4y+z=7 --> 3x + 4y - 2y + 3 = 7 --> 3x + 2y = 4 Eqn A
\n" ); document.write( "----
\n" ); document.write( "-5x+3y+8z=-31 --> -5x + 3y - 16y + 24 = -31 --> -5x - 13y = -55 Eqn B
\n" ); document.write( "=========
\n" ); document.write( "3x + 2y = 4 Eqn A
\n" ); document.write( "-5x - 13y = -55 Eqn B
\n" ); document.write( "-----
\n" ); document.write( "15x + 10y = 20 Eqn A times 5
\n" ); document.write( "-15x - 39y = -165 Eqn B times 3
\n" ); document.write( "----------------------------------- Add
\n" ); document.write( "-29y = -145
\n" ); document.write( "y = 5
\n" ); document.write( "----
\n" ); document.write( "z = -2y+3
\n" ); document.write( "Sub for y & z in Eqn A or B to find x.\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
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