document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=304400>Question 304400</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am trying to write an equation based on table data. <BR>\n" );
document.write( "X: -2, -1, 0, 1, 2<BR>\n" );
document.write( "Y: -8, -2, 0, -2, -8<BR>\n" );
document.write( "Based on the differences, I know that it should be a quadratic equation, but I do not know the proper format. How do you take the data from the table to create the equation? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #217982 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=217982\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> I am trying to write an equation based on table data. <BR>\n" );
document.write( "X: -2, -1, 0, 1, 2<BR>\n" );
document.write( "Y: -8, -2, 0, -2, -8<BR>\n" );
document.write( "-------------------------------<BR>\n" );
document.write( "Form: y = ax^2 + bx + c<BR>\n" );
document.write( "Substitute three of the x/y pairs; then solve for a, b, c:<BR>\n" );
document.write( "-8 = 4a -2b + c<BR>\n" );
document.write( "-2 =  a -b  + c<BR>\n" );
document.write( "0  = 0a +0b + c<BR>\n" );
document.write( "-----------------------<BR>\n" );
document.write( "Using the matrix function of a TI calculator I get:<BR>\n" );
document.write( "a = -2 ; b = 0 ; c = 0<BR>\n" );
document.write( "-------------------<BR>\n" );
document.write( "Equation:<BR>\n" );
document.write( "y = -2x^2<BR>\n" );
document.write( "===================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );