document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1015007>Question 1015007</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Thanks!\r<BR>\n" );
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document.write( "In which line is a mistake first made when solving the following system of equations by substitution?<BR>\n" );
document.write( "3x + y = 9<BR>\n" );
document.write( "-2x + y = 4\r<BR>\n" );
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document.write( "Line 1<BR>\n" );
document.write( "y = -3x + 9<BR>\n" );
document.write( "-2x + y = 4<BR>\n" );
document.write( "Line 2<BR>\n" );
document.write( "3x + (-3x + 9) = 9<BR>\n" );
document.write( "Line 3<BR>\n" );
document.write( "3x - 3x + 9 = 9<BR>\n" );
document.write( "Line 4<BR>\n" );
document.write( "9 = 9 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #631329 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=631329\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> -2x+y=4<BR>\n" );
document.write( "-2x-3x+9=4<BR>\n" );
document.write( "-5x=-5<BR>\n" );
document.write( "x=1<BR>\n" );
document.write( "The mistake is made in line 2.  The first line is fine, but now the y =-3x+9 has to be substituted for y in the equation -2x+y=4, not back into the first equation where of course it will be 9=9. </SPAN>\n" );
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