For a 5-dimensional vector space, I have an operator I'm working with T satisfying

(T-1)(T^2 - 4) = 0, but T =/=1 and T^2 - 4 =/= 0.

I'm not sure how to get started on this. I can find them for a matrix, but in this case I have no matrix, only an equation in T. Any push in the right direction would be great, thank you.