1. The problem statement, all variables and given/known data Verify the operator equation (d/dx + x)(d/dx - x) = d^2/dx^2 - x^2 -1 (where d is meant to be the partial derivative symbol) 2. Relevant equations None that are obvious to me? 3. The attempt at a solution The truth is i'm not really sure how i should be going about this i tried expanding the brackets to get: d^2/dx^2 + d/dx*x - d/dx*x - x^2 I didn't know whether having d/dx*x means i should differentiate or just leave it but i thought they'd cancel either way giving d^2/dx^2 - x^2 so where does the -1 come from?