How is the following operator linear??! 1. The problem statement, all variables and given/known data Is the following a linear vector function? F(r) = r - ix 2. Relevant equations A function is linear if: F(r1 + r2) = F(r1) + F(r2) AND F(ar) = aF(r) 3. The attempt at a solution F(r1 + r2) = (r1 + r2) - ix F(r1) + F(r2) = (r1 - ix) + (r2 - ix) = (r1 + r2) - 2ix According to me, F(r1 + r2) ≠ F(r1) + F(r2), but Mary L Boas says otherwise. What gives?