document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=720045>Question 720045</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the value of k so that the line containing the points (k,&#8722;7) and (6,6) is perpendicular to the line y=&#8722;2/7x+1.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #441676 by </B><A HREF=/tutors/aboutme.mpl?userid=jsmallt9><B>jsmallt9(3758)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jsmallt9><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=441676\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The slope of the line y = (2/7)x+1 is 2/7. The slope of any perpendicular line will be the negative reciprocal of the the slope of this line. So the slope of our perpendicular line will be -7/2.<br><BR>\n" );
document.write( "The slope of the line through (k, -7) and (6, 6) will be (according to the slope formula):<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%286-%28-7%29%29%2F%286-k%29 ALIGN=MIDDLE  ALT=\"%286-%28-7%29%29%2F%286-k%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "or<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=13%2F%286-k%29 ALIGN=MIDDLE  ALT=\"13%2F%286-k%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "We want the line through (k, -7) and (6, 6) to be perpendicular to y = (2/7)x+1. So its slope needs to be -7/2. Therefore:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=13%2F%286-k%29+=+-7%2F2 ALIGN=MIDDLE  ALT=\"13%2F%286-k%29+=+-7%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "Now we solve for k. Cross-multiplying we get:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=13%2A2+=+%286-k%29%2A%28-7%29 ALIGN=MIDDLE  ALT=\"13%2A2+=+%286-k%29%2A%28-7%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Simplifying:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=26+=+-42+%2B+7k ALIGN=MIDDLE  ALT=\"26+=+-42+%2B+7k\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Adding 42:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=68+=+7k ALIGN=MIDDLE  ALT=\"68+=+7k\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Dividing by 7:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=68%2F7+=+k ALIGN=MIDDLE  ALT=\"68%2F7+=+k\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );