document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1139999>Question 1139999</A>: <I><SPAN STYLE=\"word-break: break-all;\">  let: L1: y=3 and L2: x=3 prove that:slop(L1) × slop(L2) = - 1  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #760513 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=760513\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "The solution by tutor @MathLover1 did not address the conditions of the problem; and her answer is therefore very wrong.<br><BR>\n" );
document.write( "The proposition is NOT true; the product of the slopes of L1 and L2 is NOT -1.<br><BR>\n" );
document.write( "The slope of L1 is 0, and the slope of L2 is undefined.  The product of \"0\" and \"undefined\" is not -1.<br><BR>\n" );
document.write( "Two lines for which the product of the slopes is -1 are perpendicular.<br><BR>\n" );
document.write( "However, the product of the slopes of two perpendicular lines is -1 ONLY IF THE TWO LINES ARE NOT ONE HORIZONTAL AND ONE VERTICAL.<BR>\n" );
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