2.
\((1)\) 已知函数\(f(x){=}\begin{cases} 2^{x}{,} & x{\leqslant }0 \\ f(x{-}1){-}1{,} & x{ > }0 \end{cases}\),则\(f(\log_{2}9){=}\) ______ .
\((2)\) 变量\(x\)、\(y\)满足线性约束条件\(\begin{cases} 2x{+}y{\leqslant }2 \\ x{-}y{\geqslant }0 \\ y{\geqslant }0 \end{cases}\),则使目标函数\(z{=}{ax}{+}y(a{ > }0)\)取得最大值的最优解有无数个,则\(a\)的值为______ .
\((3)\) 已知焦点\(F\)为抛物线\(y^{2}{=}2{px}(p{ > }0)\)上有一点\(A(m{,}2\sqrt{2})\),以\(A\)为圆心,\(AF\)为半径的圆被\(y\)轴截得的弦长为\(2\sqrt{5}\),则\(m{=}\) ______ .
\((4)\) 如图,平面四边形\(ABCD\)中,\({AB}{=}{AD}{=}{CD}{=}1\),\({BD}{=}\sqrt{2}\),\({BD}{⊥}{CD}\),将其沿对角线\(BD\)折成四面体\(A{{{{'}}}-}{BCD}\),使平面\(A{{{{'}}}}{BD}{⊥}\)平面\({BCD}{.}\)四面体\(A{{{{'}}}-}{BCD}\)顶点在同一个球面上,则该球的体积为______ .