document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=82627>Question 82627</A>: <I><SPAN STYLE=\"word-break: break-all;\"> practice problem that is confusing me, I thought quadratic equation was x^2 not x^4 so HELP please.\r<BR>\n" );
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document.write( "x^4-10x^2+9=0 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #59223 by </B><A HREF=/tutors/aboutme.mpl?userid=kev82><B>kev82(151)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=kev82><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=59223\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Hi,<br />\r<BR>\n" );
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document.write( "You're right. This isn't a quadratic equation. But, we can turn it into one with a simple substitution. If I let <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?x^2=q\"> then <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?x^4=q^2\">. Replacing x with q gives:<br />\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?q^2-10q+9=0\"><br />\r<BR>\n" );
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document.write( "This is quadratic in q and can be factorised <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?(q-1)(q-9)=0\">. So we have two solutions for q. But remember <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?x^2=q\">. So for both values of q we have a quadratic in x. Solving these should give you the final answers of x=-3,3,-1,1. If you can't get that, write back and I'll go over the working in more detail.<br />\r<BR>\n" );
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document.write( "Hope that helps,<BR>\n" );
document.write( "Kev </SPAN>\n" );
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