document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=100792>Question 100792</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 2x2 + 3xy -4y2 when x=2 and y=4 i would like to know how they got (-80) <BR>\n" );
document.write( "if any one can break it down this is from a sample test for college online </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #73392 by </B><A HREF=/tutors/aboutme.mpl?userid=bucky><B>bucky(2189)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=bucky><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=73392\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Given:<BR>\n" );
document.write( ".<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2x%5E2+%2B+3xy+-4y%5E2 ALIGN=MIDDLE  ALT=\"2x%5E2+%2B+3xy+-4y%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "You are to evaluate this when x = 2 and y = 4<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Go to the given function and substitute 2 wherever there is an x and substitute 4 wherever there<BR>\n" );
document.write( "is a y. When you make those substitutions you get:<BR>\n" );
document.write( ".<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%282%29%5E2+%2B+3%282%29%284%29-4%284%29%5E2 ALIGN=MIDDLE  ALT=\"2%282%29%5E2+%2B+3%282%29%284%29-4%284%29%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "Notice that <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%5E2+=+4 ALIGN=MIDDLE  ALT=\"2%5E2+=+4\"   DISABLED_style= \"max-width:90%; height:auto;\" > and <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%5E2+=+16 ALIGN=MIDDLE  ALT=\"4%5E2+=+16\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "Make these substitutions and the problem then becomes:<BR>\n" );
document.write( ".<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2A4+%2B+3%2A2%2A4+-+4%2A16 ALIGN=MIDDLE  ALT=\"2%2A4+%2B+3%2A2%2A4+-+4%2A16\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "The 2 times the 4 is 8. And the 3 times 2 times 4 is 24. And the -4 times 16 is -64. Substituting<BR>\n" );
document.write( "these values reduces the problem to:<BR>\n" );
document.write( ".<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=8+%2B+24+-+64+ ALIGN=MIDDLE  ALT=\"8+%2B+24+-+64+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "and these combine to give:<BR>\n" );
document.write( ".<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-32 ALIGN=MIDDLE  ALT=\"-32\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "You are correct. Their answer of -80 is in error. Are you sure that the sign of the middle<BR>\n" );
document.write( "term of 3xy is positive? If it were negative your answer would become:<BR>\n" );
document.write( ".<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=8+-+24+-+64 ALIGN=MIDDLE  ALT=\"8+-+24+-+64\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "and that would give an answer of <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-80 ALIGN=MIDDLE  ALT=\"-80\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );