ss=StateSpaceModel[{(({{1, 1, -2}, {0, 1, 1}, {0, 0, 1}})),(({{1}, {0}, {1}})),(({{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}))},SamplingPeriod->0.1];
k=StateFeedbackGains[ss,{0,0,0}]

ListPlot[OutputResponse[{SystemsModelStateFeedbackConnect[ss,k],{3,-1,2}},{0},{t,0.4}],Joined->True,AxesOrigin->{1,0},AxesLabel-> {"t"}]