Given

$f(x,y,z)=x^{9}y{z}^n,$ find $\frac{de{l}^{2}f}{\text{d}\text{e}\text{l}\text{x}\text{d}\text{e}\text{l}\text{y}}$ and $f_2(1,1,1)$

$\frac{\text{d}\text{e}\text{l}\text{f}}{\text{d}\text{e}\text{l}\text{x}\text{d}\text{e}\text{l}\text{y}}=$

$f_1(1,1,1)=$

$\frac{de{l}^{2}f}{\text{d}\text{e}\text{l}\text{x}\text{d}\text{e}\text{l}\text{y}}=9x^{8}y{z}^6{x}^9{z}^6$;$,f_x(1,1,1)=10$

$\frac{de{l}^{2}f}{\text{d}\text{e}\text{l}\text{x}\text{d}\text{e}\text{l}\text{y}}=9x^{8}y{z}^6$;$,f_z(1,1,1)=9$

$\frac{de{l}^{2}f}{\text{d}\text{e}\text{l}\text{x}\text{d}\text{e}\text{l}\text{y}}=9x^8{z}^6$;$,f_z(1,1,1)=6$