I need to find b, c and d in a cubic equation of the form y=x(adsbygoogle = window.adsbygoogle || []).push({}); ^{3}+bx^{2}+cx+d (ie. a=1 if a is the coefficient of x^{3}). I've been given three points (-2,-13), (-1,0), (1,2). If I had a fourth piece of data i could solve the equation I suppose, but with only three I've really struggled. Here's what I've got so far:

http://img71.imageshack.us/img71/9821/matrix0iw.gif [Broken]

(1) is just the set out

(2) I've entered the data

(3) I've rearranged the equation

But when I thin input the equation on my calculator (the TI-89 Cas calc) I get a matrix in which every row has x and y in it. But that solution doesn't agree with the back of the book, which states that:

b=-2

c=0

d=3

which indicates a final equation of y=x^{3}-2x^{2}+3

I've thought of using a matrix system which ommits the top row of all three matrices, but of course that equation system isn't defined.

I'd really apprieciate any help, thanks.

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# Solving cubic equation with matrices

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