1. The problem statement, all variables and given/known data a positive definite matrix has eigenvalues λ=1 and λ=2. find the matrix 2. Relevant equations 3. The attempt at a solution I've used a 2x2 matrix with entries a0,a1,a2,a3 as the unknown matrix but no use. (As little as i know a0 and a3 should be 1 and 2 respectively; corresponding to the eigenvalues) Any ideas on how to solve this?