document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1190557>Question 1190557</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 6) Given the curve y = x^3 - 3x^2 - 9x+11, find dy/dx.Hence obtain<BR>\n" );
document.write( "a) the x-coordinates of the points where the gradient is 15,<BR>\n" );
document.write( "b) the coordinates of the points where the gradient is zero. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #822260 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=822260\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Given the curve y = x^3 - 3x^2 - 9x+11, find dy/dx.<BR>\n" );
document.write( "dy/dx = 3x^2 - 6x - 9<BR>\n" );
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document.write( "Hence obtain<BR>\n" );
document.write( "a) the x-coordinates of the points where the gradient is 15<BR>\n" );
document.write( "f'(x) = 3x^2 - 6x - 9 = 15<BR>\n" );
document.write( "3x^2 - 6x - 24 = 0<BR>\n" );
document.write( "x^2 - 2x - 8 = 0<BR>\n" );
document.write( "(x+2)*(x-4) = 0<BR>\n" );
document.write( "x = -2<BR>\n" );
document.write( "x = 4<BR>\n" );
document.write( "Find the ordinates for each x.<BR>\n" );
document.write( "---------------<BR>\n" );
document.write( "b) the coordinates of the points where the gradient is zero.<BR>\n" );
document.write( "3x^2 - 6x - 9 = 0<BR>\n" );
document.write( "Solve for x and y. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );