document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=587558>Question 587558</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me solve:  3x^2-12x-13=0 by completing the square. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #374161 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=374161\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3x%5E2-12x-13=0+ ALIGN=MIDDLE  ALT=\"+3x%5E2-12x-13=0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Add <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=13 ALIGN=MIDDLE  ALT=\"13\"   DISABLED_style= \"max-width:90%; height:auto;\" > to both sides<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3x%5E2+-+12x+=+13+ ALIGN=MIDDLE  ALT=\"+3x%5E2+-+12x+=+13+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Divide both sides by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3 ALIGN=MIDDLE  ALT=\"3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2+-+4x+=+13%2F3+ ALIGN=MIDDLE  ALT=\"+x%5E2+-+4x+=+13%2F3+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Take 1/2 of the coefficient of <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" >,<BR>\n" );
document.write( "square it, and add it to both sides<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2+-+4x+%2B+%28%28-4%29%2F2%29%5E2+=+13%2F3+%2B+%28%28-4%29%2F2%29%5E2+ ALIGN=MIDDLE  ALT=\"+x%5E2+-+4x+%2B+%28%28-4%29%2F2%29%5E2+=+13%2F3+%2B+%28%28-4%29%2F2%29%5E2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2+-+4x+%2B+%28-2%29%5E2+=+13%2F3+%2B+%28-2%29%5E2+ ALIGN=MIDDLE  ALT=\"+x%5E2+-+4x+%2B+%28-2%29%5E2+=+13%2F3+%2B+%28-2%29%5E2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2+-+4x+%2B+4+=+13%2F3+%2B+4+ ALIGN=MIDDLE  ALT=\"+x%5E2+-+4x+%2B+4+=+13%2F3+%2B+4+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2+-+4x+%2B+4+=+13%2F3+%2B+12%2F3+ ALIGN=MIDDLE  ALT=\"+x%5E2+-+4x+%2B+4+=+13%2F3+%2B+12%2F3+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2+-+4x+%2B+4+=+25%2F3+ ALIGN=MIDDLE  ALT=\"+x%5E2+-+4x+%2B+4+=+25%2F3+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%28+x+-+2+%29%5E2+=+%28+5%2Fsqrt%283%29%29%5E2+ ALIGN=MIDDLE  ALT=\"+%28+x+-+2+%29%5E2+=+%28+5%2Fsqrt%283%29%29%5E2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Take the square root of both sides<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+-+2+=+5%2Fsqrt%283%29+ ALIGN=MIDDLE  ALT=\"+x+-+2+=+5%2Fsqrt%283%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+2+%2B+5%2Fsqrt%283%29+ ALIGN=MIDDLE  ALT=\"+x+=+2+%2B+5%2Fsqrt%283%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and also<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+-+2+=+-5%2Fsqrt%283%29+ ALIGN=MIDDLE  ALT=\"+x+-+2+=+-5%2Fsqrt%283%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+2+-+5%2Fsqrt%283%29+ ALIGN=MIDDLE  ALT=\"+x+=+2+-+5%2Fsqrt%283%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "These are the 2 solutions<BR>\n" );
document.write( "------------------<BR>\n" );
document.write( "I will check by using approximate values<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+2+%2B+5%2F1.732+ ALIGN=MIDDLE  ALT=\"+x+=+2+%2B+5%2F1.732+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+2+%2B+2.8868+ ALIGN=MIDDLE  ALT=\"+x+=+2+%2B+2.8868+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+4.8868+ ALIGN=MIDDLE  ALT=\"+x+=+4.8868+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Plugging this back into original equation<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3x%5E2-12x-13=0+ ALIGN=MIDDLE  ALT=\"+3x%5E2-12x-13=0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3%2A4.8868%5E2-12%2A4.8868-13=0+ ALIGN=MIDDLE  ALT=\"+3%2A4.8868%5E2-12%2A4.8868-13=0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3%2A23.8808+-+58.6416+-+13+=+0+ ALIGN=MIDDLE  ALT=\"+3%2A23.8808+-+58.6416+-+13+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+71.6424+-+58.6416+-+13+=+0+ ALIGN=MIDDLE  ALT=\"+71.6424+-+58.6416+-+13+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+.0008+=+0+ ALIGN=MIDDLE  ALT=\"+.0008+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "I believe the error is due to rounding off<BR>\n" );
document.write( "You can check the other solution </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );