$I\in \left( \Delta  \right)\Rightarrow I\left( -1+2t;1+t;-2t \right)$ Mặt cầu đi qua A, B nên IA=IB

$\Rightarrow {{\left( -2+2t \right)}^{2}}+{{\left( -2+t \right)}^{2}}+{{\left( -2t \right)}^{2}}={{\left( 1+2t \right)}^{2}}+{{t}^{2}}+{{\left( -2t-1 \right)}^{2}}\Rightarrow t=\frac{3}{10}\Rightarrow I\left( -\frac{2}{5};\frac{13}{10};-\frac{3}{5} \right);{{R}^{2}}=\frac{521}{100}$