document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=390472>Question 390472</A>: <I><SPAN STYLE=\"word-break: break-all;\"> find the second root of the quadratic equation x^2 + 9x + k = 0 if one root is -2. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #276888 by </B><A HREF=/tutors/aboutme.mpl?userid=richard1234><B>richard1234(7193)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=richard1234><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=richard1234><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=276888\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A fast way to solve this problem is to know that the sum of the roots of a quadratic is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-b%2Fa ALIGN=MIDDLE  ALT=\"-b%2Fa\"   DISABLED_style= \"max-width:90%; height:auto;\" >, or -9 in this case. Since one of the roots is -2, the other one must be (-9) - (-2), or -7. Amazing that we don't even need to solve for k to find the other root?\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "(In general, the sum of the roots of any polynomial <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ax%5En+%2B+bx%5E%28n-1%29+%2B+... ALIGN=MIDDLE  ALT=\"ax%5En+%2B+bx%5E%28n-1%29+%2B+...\"   DISABLED_style= \"max-width:90%; height:auto;\" > is -b/a. This is one of Vieta's formulas. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );