document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1209327>Question 1209327</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Let<BR>\n" );
document.write( "f(x) = (2x + 5)/(x - 4).<BR>\n" );
document.write( "If f^{-1} is the inverse of f, what is f^{-1}(1)? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #848372 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=848372\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "(1) for tutor @ikleyn -- you have a wrong sign in your original equation....<br><BR>\n" );
document.write( "(2) The comments from tutor @ikleyn that there is no need to find the inverse function to answer this question are correct.<br><BR>\n" );
document.write( "(3) In a problem where you are in fact asked to find the inverse of a rational function, it is useful to know that the inverse of<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=%28ax%2Bb%29%2F%28cx%2Bd%29 ALIGN=MIDDLE  ALT=\"y=%28ax%2Bb%29%2F%28cx%2Bd%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "is<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=%28-dx%2Bb%29%2F%28cx-a%29 ALIGN=MIDDLE  ALT=\"y=%28-dx%2Bb%29%2F%28cx-a%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "(Note the pattern: the \"b\" and \"c\" stay where they are; the \"a\" and \"d\" switch places and both change sign.)<br><BR>\n" );
document.write( "For this problem, given<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=%282x%2B5%29%2F%28x-4%29 ALIGN=MIDDLE  ALT=\"y=%282x%2B5%29%2F%28x-4%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "the inverse is<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=%284x%2B5%29%2F%28x-2%29 ALIGN=MIDDLE  ALT=\"y=%284x%2B5%29%2F%28x-2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "So<br><BR>\n" );
document.write( "ANSWER: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=f%5E%28-1%29%281%29=%284%2B5%29%2F%281-2%29=9%2F-1 ALIGN=MIDDLE  ALT=\"f%5E%28-1%29%281%29=%284%2B5%29%2F%281-2%29=9%2F-1\"   DISABLED_style= \"max-width:90%; height:auto;\" > = -9<br><BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );