document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=117577>Question 117577</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0130501832/algebrahomeworkh></A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> how can i do this:\r<BR>\n" );
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document.write( "x-y+z=0<BR>\n" );
document.write( "3x-2y+6z=9<BR>\n" );
document.write( "-x+y-2z=21 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #85570 by </B><A HREF=/tutors/aboutme.mpl?userid=MathLover1><B>MathLover1(20850)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=MathLover1><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=MathLover1><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=85570\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x-y%2Bz=0 ALIGN=MIDDLE  ALT=\"x-y%2Bz=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >………(1)\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3x-2y%2B6z=9 ALIGN=MIDDLE  ALT=\"3x-2y%2B6z=9\"   DISABLED_style= \"max-width:90%; height:auto;\" >……………..(2)\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-x%2By-2z=21 ALIGN=MIDDLE  ALT=\"-x%2By-2z=21\"   DISABLED_style= \"max-width:90%; height:auto;\" >…………..(3)<BR>\n" );
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document.write( "In order to solve this system for <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" >, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y ALIGN=MIDDLE  ALT=\"y\"   DISABLED_style= \"max-width:90%; height:auto;\" >, and <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=z ALIGN=MIDDLE  ALT=\"z\"   DISABLED_style= \"max-width:90%; height:auto;\" >, first you need to eliminate one unknown variable. If you look at (1) and (3) you will see that <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > and <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y ALIGN=MIDDLE  ALT=\"y\"   DISABLED_style= \"max-width:90%; height:auto;\" > have opposite signs and same coefficient which is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1 ALIGN=MIDDLE  ALT=\"1\"   DISABLED_style= \"max-width:90%; height:auto;\" >; so, we can add these and eliminate <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > and <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y ALIGN=MIDDLE  ALT=\"y\"   DISABLED_style= \"max-width:90%; height:auto;\" > and find out what <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=z ALIGN=MIDDLE  ALT=\"z\"   DISABLED_style= \"max-width:90%; height:auto;\" > is.\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x-y%2Bz=0 ALIGN=MIDDLE  ALT=\"x-y%2Bz=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >………(1)<BR>\n" );
document.write( "	<BR>\n" );
document.write( "+<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-x%2By-2z=21 ALIGN=MIDDLE  ALT=\"-x%2By-2z=21\"   DISABLED_style= \"max-width:90%; height:auto;\" >…………..(3)<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+%2B%28-x%29-y+%2B+y+%2B+z+%2B+%28-2z%29=+0+%2B+21 ALIGN=MIDDLE  ALT=\"x+%2B%28-x%29-y+%2B+y+%2B+z+%2B+%28-2z%29=+0+%2B+21\"   DISABLED_style= \"max-width:90%; height:auto;\" >……….cancel <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > and <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y ALIGN=MIDDLE  ALT=\"y\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=z-2z=21 ALIGN=MIDDLE  ALT=\"z-2z=21\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-z+=+21 ALIGN=MIDDLE  ALT=\"-z+=+21\"   DISABLED_style= \"max-width:90%; height:auto;\" >………multiply both sides by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-1 ALIGN=MIDDLE  ALT=\"-1\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=z+=+-+21 ALIGN=MIDDLE  ALT=\"z+=+-+21\"   DISABLED_style= \"max-width:90%; height:auto;\" >……………………solution #1\r<BR>\n" );
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document.write( "Now plug in solution #1 in equation (1) , (2), or (3). I will choose equation (1) and multiply it by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3 ALIGN=MIDDLE  ALT=\"3\"   DISABLED_style= \"max-width:90%; height:auto;\" >, then subtract (2) from (1) to find out what <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y ALIGN=MIDDLE  ALT=\"y\"   DISABLED_style= \"max-width:90%; height:auto;\" > is.\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x-y%2Bz=0 ALIGN=MIDDLE  ALT=\"x-y%2Bz=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >………multiply both sides by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3 ALIGN=MIDDLE  ALT=\"3\"   DISABLED_style= \"max-width:90%; height:auto;\" >………….(1)\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3x-2y%2B6z=9 ALIGN=MIDDLE  ALT=\"3x-2y%2B6z=9\"   DISABLED_style= \"max-width:90%; height:auto;\" >……………..(2)<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3x-3y%2B3z=0 ALIGN=MIDDLE  ALT=\"3x-3y%2B3z=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >………………….(1)………. subtract (2) from (1)<BR>\n" );
document.write( "-<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3x-2y%2B6z=9 ALIGN=MIDDLE  ALT=\"3x-2y%2B6z=9\"   DISABLED_style= \"max-width:90%; height:auto;\" >……………..(2)<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3x-3x-3y-%28-2y%29%2B3%28-21%29-6%28-21%29=0-9 ALIGN=MIDDLE  ALT=\"3x-3x-3y-%28-2y%29%2B3%28-21%29-6%28-21%29=0-9\"   DISABLED_style= \"max-width:90%; height:auto;\" >……<BR>\n" );
document.write( " <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-3y%2B2y-63%2B126=-9 ALIGN=MIDDLE  ALT=\"-3y%2B2y-63%2B126=-9\"   DISABLED_style= \"max-width:90%; height:auto;\" >……\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-y%2B63=-9 ALIGN=MIDDLE  ALT=\"-y%2B63=-9\"   DISABLED_style= \"max-width:90%; height:auto;\" >……\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-y=-9-63 ALIGN=MIDDLE  ALT=\"-y=-9-63\"   DISABLED_style= \"max-width:90%; height:auto;\" >……\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-y=-72 ALIGN=MIDDLE  ALT=\"-y=-72\"   DISABLED_style= \"max-width:90%; height:auto;\" >……multiply both sides by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-1 ALIGN=MIDDLE  ALT=\"-1\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=72 ALIGN=MIDDLE  ALT=\"y=72\"   DISABLED_style= \"max-width:90%; height:auto;\" >……solution #2\r<BR>\n" );
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document.write( "Now choose either one of the three equations, plug in values for <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y ALIGN=MIDDLE  ALT=\"y\"   DISABLED_style= \"max-width:90%; height:auto;\" > and <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=z ALIGN=MIDDLE  ALT=\"z\"   DISABLED_style= \"max-width:90%; height:auto;\" > and find out what <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > is.\r<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x-y%2Bz=0 ALIGN=MIDDLE  ALT=\"x-y%2Bz=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >…………………………….(1)\r<BR>\n" );
document.write( "<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=y-z ALIGN=MIDDLE  ALT=\"x=y-z\"   DISABLED_style= \"max-width:90%; height:auto;\" >……\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=72-%28-21%29 ALIGN=MIDDLE  ALT=\"x=72-%28-21%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >……\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=72%2B21 ALIGN=MIDDLE  ALT=\"x=72%2B21\"   DISABLED_style= \"max-width:90%; height:auto;\" >……\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+93 ALIGN=MIDDLE  ALT=\"x+=+93\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Check:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x-y+%2Bz+=0 ALIGN=MIDDLE  ALT=\"x-y+%2Bz+=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >……..............(1)\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=93-72+%2B%28-21%29+=0 ALIGN=MIDDLE  ALT=\"93-72+%2B%28-21%29+=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >……\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=93-72-21=0 ALIGN=MIDDLE  ALT=\"93-72-21=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >……\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=93-93=0 ALIGN=MIDDLE  ALT=\"93-93=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >……\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0+=+0 ALIGN=MIDDLE  ALT=\"0+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3x-2y+%2B6z+=9 ALIGN=MIDDLE  ALT=\"3x-2y+%2B6z+=9\"   DISABLED_style= \"max-width:90%; height:auto;\" >……..............(2)\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3%2893%29-2%2872%29+%2B6%28-21%29+=9 ALIGN=MIDDLE  ALT=\"3%2893%29-2%2872%29+%2B6%28-21%29+=9\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=279-144-126+=9 ALIGN=MIDDLE  ALT=\"279-144-126+=9\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=279-270+=9 ALIGN=MIDDLE  ALT=\"279-270+=9\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=9++=+9 ALIGN=MIDDLE  ALT=\"9++=+9\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Check …(3)… by yourself\r<BR>\n" );
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document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );