document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1163930>Question 1163930</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a parabola with the x intercepts at (-1, 0) and (3, 0) which passes through the point (1, -8) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #788181 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=788181\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a parabola with the x intercepts at (-1, 0) and (3, 0) which passes through the point (1,-8)<BR>\n" );
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document.write( "y = ax^2 + bx + c is the parabola<BR>\n" );
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document.write( "At (-1,0):<BR>\n" );
document.write( "0 = a*(-1)^2 -b + c<BR>\n" );
document.write( "a - b + c = 0  ------ Eqn 1<BR>\n" );
document.write( "========================<BR>\n" );
document.write( "At (3,0):<BR>\n" );
document.write( "0 = a*9 + 3b + c  <BR>\n" );
document.write( "9a + 3b + c = 0   ---------- Eqn 2<BR>\n" );
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document.write( "At (1,-8):<BR>\n" );
document.write( "-8 = a + b + c<BR>\n" );
document.write( "a + b + c = -8 ---- Eqn 3<BR>\n" );
document.write( "a - b + c = 0  ------ Eqn 1<BR>\n" );
document.write( "----------------------------- Subtract<BR>\n" );
document.write( "2b = -8<BR>\n" );
document.write( "b = -4<BR>\n" );
document.write( "=========================<BR>\n" );
document.write( "0 = a*9 + 3b + c  ---------- Eqn 2<BR>\n" );
document.write( "9a + 3b + c = 0<BR>\n" );
document.write( "9a + c = 12<BR>\n" );
document.write( " a + c = -4<BR>\n" );
document.write( "-------------------------- Subtract<BR>\n" );
document.write( "8a = 16<BR>\n" );
document.write( "a = 2<BR>\n" );
document.write( "=================<BR>\n" );
document.write( "a - b + c = 0  ------ Eqn 1<BR>\n" );
document.write( "2 + 4 + c = 0<BR>\n" );
document.write( "c = -6<BR>\n" );
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document.write( "2x^2 - 4x - 6 = 0 is the parabola<BR>\n" );
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document.write( "Another method:<BR>\n" );
document.write( "<PRE STYLE=\"white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;\">\r\n" );
document.write( "| x   x^2   y   1|  \r\n" );
document.write( "|-1    1    0   1|\r\n" );
document.write( "| 3    9    0   1| = 0\r\n" );
document.write( "| 1    1   -8   1|\r\n" );
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document.write( "</PRE><BR>\n" );
document.write( "This method is easily made into an Excel sheet.\r<BR>\n" );
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document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );