Given $f(x,y)=-5x^2+4x^2{y}^5+5y^4,$ find

$\frac{\text{d}\text{e}\text{l}\text{z}}{\text{d}\text{e}\text{l}\text{x}}=f_x(x,y)=$

$\frac{\text{d}\text{e}\text{l}\text{z}}{\text{d}\text{e}\text{l}\text{y}}=f_y(x,y)=$

$\frac{de{l}^{2}z}{del{x}^2}=f_{}(x,y)=$

$\frac{de{l}^{2}z}{\text{d}\text{e}\text{l}\text{y}\text{d}\text{e}\text{l}\text{x}}=f_{xy}(x,y)=$