document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=443064>Question 443064</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I do not want an answer to the following problem. I did the work, and I am not getting the right answer. I would like to know where I made my mistake so that I can get the correct answer. Thank you. \r<BR>\n" );
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document.write( "Month	Share Value (in dollars)<BR>\n" );
document.write( "0	55<BR>\n" );
document.write( "3	16<BR>\n" );
document.write( "5	0<BR>\n" );
document.write( "7	-8<BR>\n" );
document.write( "9	-8<BR>\n" );
document.write( "11	0<BR>\n" );
document.write( "13	16<BR>\n" );
document.write( "15	40\r<BR>\n" );
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document.write( "1.	Using the table above, find the quadratic equation that represents the monthly value of a share of ACME Corporation since January 2009. Use the variable x to represent the number of months after January 2009 and the variable y to represent the monthly value.\r<BR>\n" );
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document.write( "I used the points (0,55),(5,0), and (11,0) to come up with the quadratic equation. I used (0,55) to solve for c in the equation ax^2+bx+c=y. I got 55 for c. I plugged that into the equation with (5,0) for x and y. I got 25a+5b+55=0, and (11,0) to get 121a+11b+55=y. I multiplied the first equation by -11, and the second one was multiplied by 5 to cancel out b and solve for a. The equation I ended up with is x^2-5x+55, but I do not get a true equation when I plug in the points. Please help me understand what I did wrong. This is due tomorrow. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #305693 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=305693\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> I do not want an answer to the following problem. I did the work, and I am not getting the right answer. I would like to know where I made my mistake so that I can get the correct answer. Thank you. <BR>\n" );
document.write( "Month Share Value (in dollars)<BR>\n" );
document.write( "0 55<BR>\n" );
document.write( "3 16<BR>\n" );
document.write( "5 0<BR>\n" );
document.write( "7 -8<BR>\n" );
document.write( "9 -8<BR>\n" );
document.write( "11 0<BR>\n" );
document.write( "13 16<BR>\n" );
document.write( "15 40 <BR>\n" );
document.write( "1. Using the table above, find the quadratic equation that represents the monthly value of a share of ACME Corporation since January 2009. Use the variable x to represent the number of months after January 2009 and the variable y to represent the monthly value.<BR>\n" );
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document.write( "I ran a Quadratic Regression program against the data and got<BR>\n" );
document.write( "the following: y = x^2-16x+55, which is the correct equation.<BR>\n" );
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document.write( "I used the points (0,55),(5,0), and (11,0) to come up with the quadratic equation. I used (0,55) to solve for c in the equation ax^2+bx+c=y. I got 55 for c. I plugged that into the equation with (5,0) for x and y. I got 25a+5b+55=0, and (11,0) to get 121a+11b+55=y. I multiplied the first equation by -11, and the second one was multiplied by 5 to cancel out b and solve for a. The equation I ended up with is x^2-5x+55, but I do not get a true equation when I plug in the points. Please help me understand what I did wrong. This is due tomorrow.<BR>\n" );
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document.write( "Using your method with (0,55),(5,0),(11,0) on ax^2+bx+c = y, I get:<BR>\n" );
document.write( "(0,55): 0  +  0  + 1  = 55<BR>\n" );
document.write( "(5,0):: 25 +  5  + 1  = 0<BR>\n" );
document.write( "(11,0): 121+ 11  + 1  = 0<BR>\n" );
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document.write( "Using a matrix method on that I get:<BR>\n" );
document.write( "a =1; b = -16 ; c = 55<BR>\n" );
document.write( "Which gives me y = x^2-16x+55 as the proper answer.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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