document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=135329>Question 135329</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Use the graph of   y=x^2-2x-8, does this function have a maximum and minimum and if so what are they? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #99155 by </B><A HREF=/tutors/aboutme.mpl?userid=Earlsdon><B>Earlsdon(6294)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Earlsdon><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=99155\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Does the graph of:<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+x%5E2-2x-8 ALIGN=MIDDLE  ALT=\"y+=+x%5E2-2x-8\"   DISABLED_style= \"max-width:90%; height:auto;\" > have a maximumum and minimum?<BR>\n" );
document.write( "Well, it may have a maximum or it may have a minimum, but it doesn't have both!<BR>\n" );
document.write( "The graph of a quadratic equation (<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+ax%5E2%2Bbx%2Bc ALIGN=MIDDLE  ALT=\"y+=+ax%5E2%2Bbx%2Bc\"   DISABLED_style= \"max-width:90%; height:auto;\" >), such as this, is called a \"parabola\" and a parabola has a maximum or a minimum depending upon whether it opens upwards (has a minimum) or opens downwards (has a maximum).<BR>\n" );
document.write( "You can tell which way the parabola opens by inspecting the coefficient of the <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5E2 ALIGN=MIDDLE  ALT=\"x%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > term, which is +1 in your problem.<BR>\n" );
document.write( "If this coefficient is positive, then the parabola opens upwards and the graph has a minimum.<BR>\n" );
document.write( "If the coefficient is negative,then the parabola opens downwards and the graph has a maximum.<BR>\n" );
document.write( "The maximum/minimum point (also known as the \"vertex\") can be found as follows:<BR>\n" );
document.write( "The x-coordinate of this point is:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%28-b%29%2F2a ALIGN=MIDDLE  ALT=\"x+=+%28-b%29%2F2a\"   DISABLED_style= \"max-width:90%; height:auto;\" > The a is the coefficient of the <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5E2 ALIGN=MIDDLE  ALT=\"x%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > term and the b is the coefficient of the <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > term. <BR>\n" );
document.write( "In your equation, a = 1 and b = -2, so...<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+-%28-2%29%2F2%281%29 ALIGN=MIDDLE  ALT=\"x+=+-%28-2%29%2F2%281%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+2%2F2 ALIGN=MIDDLE  ALT=\"x+=+2%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+1 ALIGN=MIDDLE  ALT=\"x+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" > This is the x-coordinate of the vertex.<BR>\n" );
document.write( "To find the y-coordinate, substitute x = 1 into the given quadratic equation and solve for y:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+x%5E2-2x-8 ALIGN=MIDDLE  ALT=\"y+=+x%5E2-2x-8\"   DISABLED_style= \"max-width:90%; height:auto;\" > Substitute x = 1.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+%281%29%5E2-2%281%29-8 ALIGN=MIDDLE  ALT=\"y+=+%281%29%5E2-2%281%29-8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+1-2-8 ALIGN=MIDDLE  ALT=\"y+=+1-2-8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+-9 ALIGN=MIDDLE  ALT=\"y+=+-9\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The vertex (or the minimum in this case) is at (1, -9)<BR>\n" );
document.write( "Let's see what the graph looks like:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28400%2C400%2C-5%2C5%2C-10%2C5%2Cx%5E2-2x-8%29 ALIGN=MIDDLE  ALT=\"graph%28400%2C400%2C-5%2C5%2C-10%2C5%2Cx%5E2-2x-8%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );