9.已知集合A={x∈Z∣x⩽2},B={y∣y=x2,x∈A}A=\left\{{x\in {Z}\vert {\sqrt{x}\leqslant 2}}\right\},B=\left\{{y\vert {y={x^2},x\in A}}\right\}A={x∈Z∣x⩽2},B={y∣y=x2,x∈A},则A⋃B=(A\bigcup B=(A⋃B=( )))