$2\mathrm{.}3$ Find $\frac{d^{2}y}{d{x}^2}$ in its simplest form if $sin{h}^{-1}(x^{2}y)=\sqrt[\phantom{2}]{1+x^4{y}^2}$

$2\mathrm{.}4$ If $z=co{s}^{-1}(\frac{y}{\sqrt[\phantom{2}]{x^2+y^2}})$ find $\frac{\text{d}\text{e}\text{l}\text{z}}{\text{d}\text{e}\text{l}\text{y}}$ and $\frac{de{l}^{2}z}{\text{d}\text{e}\text{l}\text{x}\text{d}\text{e}\text{l}\text{y}}$ in its simplest form

$2\mathrm{.}5$ If $z=ta{n}^{-1}(x{y}^2),$ find $\frac{de{l}^{2}z}{del{x}^2}$ and $\frac{de{l}^{2}z}{\text{d}\text{e}\text{l}\text{y}\text{d}\text{e}\text{l}\text{x}}$ in their simplest forms

$(6)$