15. [-/1 Points] DETAILS SCALCET9 14.2.053.MI.NVA MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Use polar coordinates to find the limit. [If (r, 0) are polar coordinates of the point (x, y) with r 2 0, note that r - 0 as (x, y) - (0, 0).] (If an answer does not exist, enter DNE.) 6e- x2 - 2 lim - 6 ( x, y) - (0, 0) x2+ 12 Need Help? Watch It Master It Submit Answer 16. [-/2 Points] DETAILS SCALCET9 14.3.009. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Find the first partial derivatives of the function. f ( x, y) = x8+ 9xy3 fx ( x, y ) = fy ( x, y ) = Need Help? Read It Submit Answer 17. [-/2 Points] DETAILS SCALCET9 14.3.013. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Find the first partial derivatives of the function. z = In(x + to ) oz ax az at Need Help? Read It Submit Answer 18. [-/2 Points] DETAILS SCALCET9 14.3.024. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Find the first partial derivatives of the function. f( x, y) = x8y fx ( x, y ) = f ( x, y ) = Need Help? Read It Submit Answer 19. [-/1 Points] DETAILS SCALCET9 14.3.038. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Find the indicated partial derivative. f ( x , y ) = y sin -1 ( xy ) ; ry ( 4 . * ) 4 ( 4 , # ) =