1. The problem statement, all variables and given/known data in this problem , we know that Q (flow rate ) has power of 2 , hf = k(Q^2) , shouldnt the hf = k(Q^2) has positive value ? 2. Relevant equations 3. The attempt at a solution since (554)(-40^2) will become positive , same thing goes to hf / Q , when the hf = positive , the hf / Q will become hf / Q divided by Q(has negative value ) , so the hf / Q will have negative value , am i right ?