If $f(x,y)=x^{3}y+2xy+x{y}^3,$ find the following: $[1$ point each$]$

a$)f_{}(x,y)$

b$)f_{yy}(x,y)$

c$)f_{xy}(x,y)$

d$)f_{yx}(x,y)$

If $f(x,y)=x^2{e}^{xy},$ find the following: $[2$ points each$]$

a$)f_x(x,y)$

b$)f_y(x,y)$

If $f(x,y)=\frac{x^2}{y},$ find the following: $[1$ point each$]$

a$)f_x(x,y)$

b$)f_y(x,y)$