document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=280644>Question 280644</A>: <I><SPAN STYLE=\"word-break: break-all;\"> solve by elimination method<BR>\n" );
document.write( "7r-2s=31<BR>\n" );
document.write( "2r+7s=77 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #203976 by </B><A HREF=/tutors/aboutme.mpl?userid=oberobic><B>oberobic(2304)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=oberobic><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=203976\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Solving simultaneous equations by the elimination method means to align the equations and add or subtract them to find one value.  Then substitute this value to find the other.  And so forth.<BR>\n" );
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document.write( "7r - 2s = 31<BR>\n" );
document.write( "2r + 7s = 77<BR>\n" );
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document.write( "The least common multiple of 2 and 7 is 14,<BR>\n" );
document.write( "so multiply the first equation by 7 and the second by 2<BR>\n" );
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document.write( "7(7r +2s) = 7(31)<BR>\n" );
document.write( "49r - 14s = 217<BR>\n" );
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document.write( "2(2r +7s) = 2(77)<BR>\n" );
document.write( "4r +14s = 154<BR>\n" );
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document.write( "So now we have two new equations...<BR>\n" );
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document.write( "49r - 14s = 217<BR>\n" );
document.write( "4r + 14s = 154<BR>\n" );
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document.write( "adding<BR>\n" );
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document.write( "53r = 371<BR>\n" );
document.write( "r = 7<BR>\n" );
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document.write( "substituting into one of the equations, we can find 's'<BR>\n" );
document.write( "7r -2s = 31<BR>\n" );
document.write( "7(7) -2s = 31<BR>\n" );
document.write( "-2s = 31 - 49<BR>\n" );
document.write( "-2s = -18<BR>\n" );
document.write( "s = 9<BR>\n" );
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document.write( "check by substituting in the second equation<BR>\n" );
document.write( "2r + 7s = 77 ??<BR>\n" );
document.write( "2r = 2*7 = 14<BR>\n" );
document.write( "7s = 7*9 = 63<BR>\n" );
document.write( "14 + 63 = 77<BR>\n" );
document.write( "Yes!<BR>\n" );
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document.write( "Answer:<BR>\n" );
document.write( "r = 7<BR>\n" );
document.write( "s = 9<BR>\n" );
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document.write( "Done. </SPAN>\n" );
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