1. The problem statement, all variables and given/known data x^2 + y^2 < 1 Find the partial derivatives of the function. 2. Relevant equations x^2 + y^2 < 1 3. The attempt at a solution @f/@x = 2x = 0 @f/@y = 2y = 0 4. Their solution @f/@x = 2x = 0 @f/@y = 2y + 1 = 0 5. My Problem I don't see how / why they get 2y + 1 for the partial of y????