document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=154856>Question 154856</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0073268623/algebrahomeworkh>elementary and intermediate algebra</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> I have tried working this problem but can't figure out, please help. Which numbers cannot be used in place of the variable in each rational expression?<BR>\n" );
document.write( "2x+3<BR>\n" );
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document.write( "x^2-16\r<BR>\n" );
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document.write( "Thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #114020 by </B><A HREF=/tutors/aboutme.mpl?userid=scott8148><B>scott8148(6628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=scott8148><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=scott8148><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=114020\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> usually, numbers which are not allowed are those which cause things to be undefinable\r<BR>\n" );
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document.write( "division by zero is the most common no-no\r<BR>\n" );
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document.write( "looking at the denominator of the fraction; if x^2 equals 16, then the denominator is zero\r<BR>\n" );
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document.write( "so, x can't be 4 or -4 </SPAN>\n" );
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