document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=986526>Question 986526</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Let line l1 be the graph of 5x + 8y = -9. Line l2 is perpendicular to line l1 and passes through the point (10,10). If line l2 is the graph of the equation y=mx +b, then find m+b.\r<BR>\n" );
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document.write( "This makes no sense to me. Help?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #607293 by </B><A HREF=/tutors/aboutme.mpl?userid=Cromlix><B>Cromlix(4381)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Cromlix><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=Cromlix><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=607293\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Hi there,<BR>\n" );
document.write( "First of all rearrange 5x + 8y = -9<BR>\n" );
document.write( "into the form:<BR>\n" );
document.write( "y = mx + b<BR>\n" );
document.write( "5x + 8y = -9<BR>\n" );
document.write( "8y = -5x -9<BR>\n" );
document.write( "y = -5/8x - 9/8<BR>\n" );
document.write( "m is the gradient and equals<BR>\n" );
document.write( "here -5/8<BR>\n" );
document.write( "b is the y coordinate of the<BR>\n" );
document.write( "line's intersection with the 'y' axis.<BR>\n" );
document.write( "here -9/8<BR>\n" );
document.write( "..................<BR>\n" );
document.write( "Lines that are perpendicular to one another<BR>\n" );
document.write( "have gradients that multiply together to give -1<BR>\n" );
document.write( "m1 x m2 = -1<BR>\n" );
document.write( "To find the gradient (m) of line 12<BR>\n" );
document.write( "-5/8 x m2 = -1<BR>\n" );
document.write( "m2 = 8/5<BR>\n" );
document.write( "Now using the line equation:<BR>\n" );
document.write( "y - b = m(x - a)<BR>\n" );
document.write( "Where m = 8/5<BR>\n" );
document.write( "(a,b) -> (10, 10)<BR>\n" );
document.write( "y - 10 = 8/5(x - 10)<BR>\n" );
document.write( "y - 10 = 8/5x - 80/5<BR>\n" );
document.write( "y = 8/5x - 80/5 + 50/5 (10)<BR>\n" );
document.write( "y = 8/5x - 30/5......this is line 12<BR>\n" );
document.write( "Now you can report that m = 8/5<BR>\n" );
document.write( "and b = -30/5<BR>\n" );
document.write( "m + b<BR>\n" );
document.write( "So 8/5 + (-30/5) = -22/5<BR>\n" );
document.write( "Hope this helps :-) </SPAN>\n" );
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