In what direction is the derivative of (x,y) = xy + y² at P(4,9) equal to zero?
Select the correct choice below and, if necessary, fill in the answer box to complete your choice.
A. u = ___ (Simplify your answer. Use a comma to separate answers as needed. Type your answer in terms of i and j.)
B. There is no solution.
Select the correct choice below and, if necessary, fill in the answer box to complete your choice.
A. u = ___ (Simplify your answer. Use a comma to separate answers as needed. Type your answer in terms of i and j.)
B. There is no solution.