document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=424220>Question 424220</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find all numbers for which the rational expression is not defined.  Separate by comma if needed.\r<BR>\n" );
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document.write( "x^2-4/x^2+4x-21 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #295805 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=295805\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find all numbers for which the rational expression is not defined. Separate by comma if needed. <BR>\n" );
document.write( "x^2-4/x^2+4x-21<BR>\n" );
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document.write( "Not defined if x^2+4x-21 = 0<BR>\n" );
document.write( "Factor:<BR>\n" );
document.write( "x^2+7x-3x-21 = 0<BR>\n" );
document.write( "x(x+7)-3(x+7) = 0<BR>\n" );
document.write( "(x+7)(x-3) = 0<BR>\n" );
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document.write( "Undefined when x = -7 or x = 3<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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