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Homework Statement
Let T be the linear operator on R3 that has the given matrix A relative to the basis A = {(1,0,0), (1,1,0), (1,1,1)}. a) Determine whether T can be represented by a diagonal matrix, and b) whenever possible, find a diagonal matrix and a basis of R3 such that T is represented by the diagonal matrix relative to the basis.
A = [tex]
\begin{bmatrix}8&5&-5\\5&8&-5\\15&15&-12 \end{bmatrix}
[/tex]
Homework Equations
The Attempt at a Solution
a) So first I find the eigenvalues I get {3, 3, -2}, then I check the eigenspace for each value and see that the dimension of the kernel corresponds to the multiplicity (3 has dimKer = 2, -2 has dimKer = 1), so then there is a matrix P such that A is diagonalized by P-1AP. So the answer is Yes.
b) I don't really understand what it is asking me to do.. Can't I just use the eigenvectors as a basis for R3? I don't understand what this basis is I'm supposed to find and how to get T "represented by the diagonal matrix relative to the basis"..
What do I do with the given basis?