Solving for Roots of a Polynomial Equation

[transgalactic]

i added my question and how i thought to solve it in the

attached link



http://img135.imageshack.us/my.php?image=img8254gl6.jpg

 

[Dick]

Just writing 'there is no minimal polynomial' isn't much of a try. Form the matrix M-x*I and take it's determinant to get the characteristic polynomial and then factor to see if there are repeated factors you can drop.

 

[HallsofIvy]

Having concluded, correctly, that M_T is
\left[\begin{array}{cccc} 0 & 0 & 0 & 1 \\ 0 & 0 & 1 & 0 \\ 0 & 1 & 0 & 0 \\ 1 & 0 & 0 & 0 \end{array}\right]
How can you declare that M_T v= 0? For all v? By the definition of M, M<1, 0, 0, 0>= <0, 0, 0, 1>. The only matrix that takes every vector to 0 is the 0 matrix! And every matrix except the 0 vector has a minimal polynomial. As Dick said, the characteristic polynomial is given by
\left|\begin{array}{cccc} -\lambda &amp; 0 &amp; 0 &amp; 1 \\ 0 &amp; -\lambda &amp; 1 &amp; 0 \\ 0 &amp; 1 &amp; -\lambda &amp; 0 \\ 1 &amp; 0 &amp; 0 &amp; -\lambda \end{array}\right|

Take out any repeated factors to get the minimal polynomial.

 

[transgalactic]

i solved it but..

i got lamda in the dinominator
and no termes in a power that's higher than 1

http://img528.imageshack.us/my.php?image=img8256dt0.jpg

??

 

[HallsofIvy]

You have \lambda^5- \lambda^2+ \lambda- 1 and then a arrow pointing to
(\lambda^2- 1)(\lambda^3+ 1)/\lambda. How did you go from the first to the second? Oh, and since the determinant you are evaluating only has 4 \lambda s in it, how are you getting \lambda^5?

 

[transgalactic]

i was looking for numbers which make the hole thing 0

i put 1 and -1
and then i get
L=lamda
(L-1)(L+1)(ax^3+bx^2+cx+d)

i opened the colls and equalized the coeffishents
and fount the a b c d

also i divided by L because i multiplied some line by L
so the determinant must be divided by L

what now??

and also can you please answer on my PM about the question
of the transformation
i really want to understand this thing from top to bottom