2.11 The following input-output pairs have been observed during the operation of a linear system: x1?(n)={?1,2,1}???y1?(n)={1,2,?1,0,1}x2?(n)={1,?1,?1}???y2?(n)={?1,1,0,2}x3?(n)={0,1,1}???y3?(n)={1,2,1}? Can you draw any conclusions about the time invariance of this system?