document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=917949>Question 917949</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 7x-6y=-12<BR>\n" );
document.write( "6x+7y=99<BR>\n" );
document.write( "The directions are solve by the elimination method.<BR>\n" );
document.write( "I have tried by multiplying the top equation by 7 and the bottom by 6 since there was already a negative on top. I then got 49x-42y=-84 and 36x+42y=594 . I then added them together and got 85x=510 which equals x=6. Then I plugged 6 in for x In the equation 7x-6y=-12 and got y=-9. <BR>\n" );
document.write( "But when I put in the answer in mathxl, it said it was wrong. Please help me figure out what I did wrong and understand how to work this problem. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #556861 by </B><A HREF=/tutors/aboutme.mpl?userid=KMST><B>KMST(5328)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=KMST><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=KMST><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=556861\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> When you plugged 6 in for x In the equation <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7x-6y=-12 ALIGN=MIDDLE  ALT=\"7x-6y=-12\"   DISABLED_style= \"max-width:90%; height:auto;\" > , you should get<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7%2A6-6y=-12 ALIGN=MIDDLE  ALT=\"7%2A6-6y=-12\"   DISABLED_style= \"max-width:90%; height:auto;\" >---><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=42-6y=-12 ALIGN=MIDDLE  ALT=\"42-6y=-12\"   DISABLED_style= \"max-width:90%; height:auto;\" >---><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=42%2B12-6y=0 ALIGN=MIDDLE  ALT=\"42%2B12-6y=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >---><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=54-6y=0 ALIGN=MIDDLE  ALT=\"54-6y=0\"   DISABLED_style= \"max-width:90%; height:auto;\" >---><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=54=6y ALIGN=MIDDLE  ALT=\"54=6y\"   DISABLED_style= \"max-width:90%; height:auto;\" >---><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=54%2F6=y ALIGN=MIDDLE  ALT=\"54%2F6=y\"   DISABLED_style= \"max-width:90%; height:auto;\" >---><IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight%28y=9%29 ALIGN=MIDDLE  ALT=\"highlight%28y=9%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > .<BR>\n" );
document.write( "That checks out, because when you plug <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=6 ALIGN=MIDDLE  ALT=\"x=6\"   DISABLED_style= \"max-width:90%; height:auto;\" > and <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=9 ALIGN=MIDDLE  ALT=\"y=9\"   DISABLED_style= \"max-width:90%; height:auto;\" > back into the original equations, you get<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7%2A6-6%2A9=42-54=-12 ALIGN=MIDDLE  ALT=\"7%2A6-6%2A9=42-54=-12\"   DISABLED_style= \"max-width:90%; height:auto;\" > and <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=6%2A6%2B7%2A9=36%2B63=99 ALIGN=MIDDLE  ALT=\"6%2A6%2B7%2A9=36%2B63=99\"   DISABLED_style= \"max-width:90%; height:auto;\" > .<BR>\n" );
document.write( "You got y=-9 because plus and minus signs sometimes turn into each other just to trip students.<BR>\n" );
document.write( "It happens to all of us (or at least to most of us).<BR>\n" );
document.write( "It did cost me an exam, mostly because instead of moving on to the next problem, I kept working on and reviewing the same problem where I had realized something was off. </SPAN>\n" );
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