document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1122784>Question 1122784</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Write a quadratic model for (-4,8) (-1,5) (1,13) \r<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #739011 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=739011\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Write a quadratic model for (-4,8) (-1,5) (1,13) <BR>\n" );
document.write( "Using the form ax^2 + bx + c = y, write an equation for each x,y pair<BR>\n" );
document.write( "(-4,8)<BR>\n" );
document.write( "(-4^2)a - 4x + c = 8<BR>\n" );
document.write( "16a - 4b + c = 8<BR>\n" );
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document.write( "(-1,5)<BR>\n" );
document.write( "a - b + c = 5<BR>\n" );
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document.write( "(1,13)<BR>\n" );
document.write( "a + b + c = 13<BR>\n" );
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document.write( "Using elimination on the last two equations<BR>\n" );
document.write( "a + b + c = 13<BR>\n" );
document.write( "a - b + c = 5<BR>\n" );
document.write( "--------------subtraction eliminates a & c, find b<BR>\n" );
document.write( "0 + 2b + 0 = 8<BR>\n" );
document.write( "2b = 8<BR>\n" );
document.write( "b = 4 <BR>\n" );
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document.write( "Replace b in the 1st and 3rd equations<BR>\n" );
document.write( "16a -4(4) + c = 8<BR>\n" );
document.write( "16a + c = 8 + 16<BR>\n" );
document.write( "16a + c = 24<BR>\n" );
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document.write( "a + 4 + c = 13<BR>\n" );
document.write( "a + c = 9<BR>\n" );
document.write( "Use elimination on these two equations <BR>\n" );
document.write( "16a + c = 24<BR>\n" );
document.write( "a  + c  = 9<BR>\n" );
document.write( "------------subtraction eliminates c<BR>\n" );
document.write( "15a = 15<BR>\n" );
document.write( "a = 1<BR>\n" );
document.write( "Find c using a + c = 9<BR>\n" );
document.write( "1 + c = 9<BR>\n" );
document.write( " c = 8<BR>\n" );
document.write( "the equation: Y = x^2 + 4x + 8 </SPAN>\n" );
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