document.write( "Question 1091455: Find the point of intersection of the planes x + y + z = 12, 2x + y - z = 20, and -x - y + 4z = - 17 \n" ); document.write( "

Algebra.Com's Answer #705855 by Alan3354(69443) $\"\"$ $\"About$

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x + y + z = 12
\n" ); document.write( "2x + y - z = 20
\n" ); document.write( "-x - y + 4z = - 17
\n" ); document.write( " x + y + z = 12
\n" ); document.write( "------------------------- Add eqn 1 & 3
\n" ); document.write( "5z = -5
\n" ); document.write( "z = -1
\n" ); document.write( "---------
\n" ); document.write( " x + y + z = 12
\n" ); document.write( "2x + y - z = 20
\n" ); document.write( "================
\n" ); document.write( " x + y = 13
\n" ); document.write( "2x + y = 19
\n" ); document.write( "---------------\r
\n" ); document.write( "\n" ); document.write( "Subtract
\n" ); document.write( "-x = -6
\n" ); document.write( "x = 6
\n" ); document.write( "----------------
\n" ); document.write( " x + y + z = 12
\n" ); document.write( " 6 + y - 1 = 12
\n" ); document.write( "y = 7
\n" ); document.write( "--> intersection at (6,7,-1) \n" ); document.write( "

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