document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=493725>Question 493725</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Really need some help please.\r<BR>\n" );
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document.write( "Given the quadratic function f(x) = x2 – 18x + 81, find a value of x such that f(x) = 16. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #335434 by </B><A HREF=/tutors/aboutme.mpl?userid=MRperkins><B>MRperkins(300)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=MRperkins><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=MRperkins><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=335434\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> let f(x)=16, and substitute it into the equation<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=16=x%5E2-18x%2B81 ALIGN=MIDDLE  ALT=\"16=x%5E2-18x%2B81\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0=x%5E2-18x%2B65 ALIGN=MIDDLE  ALT=\"0=x%5E2-18x%2B65\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "factor and get <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28x-13%29%28x-5%29=0 ALIGN=MIDDLE  ALT=\"%28x-13%29%28x-5%29=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "zero product rule says that one of them, (x-13) or (x-5) must be 0 for this to be true, so set each  DISABLED_event_one=  to zero and solve<BR>\n" );
document.write( "x=13, x=5<BR>\n" );
document.write( "x=5,13<BR>\n" );
document.write( "You can then check these by substituting them back into the original equation. </SPAN>\n" );
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