1. The problem statement, all variables and given/known data The problem: Attached as TheProblem.jpg. Solution: 2. Relevant equations xT A x 3. The attempt at a solution I computed the product and got 9x22 + 4 x1x1 + 4x12. I'm thinking that I might need to show that that obtained polynomial must be below zero since we want to show that matrix A is not a positive definite matrix but, I don't know where to go from here. Any input would be appreciated!