Ac = {{0, 1, 0}, {0, 0, 
          1}, {-2, -1, -1}}
Bc = {{0}, {0}, {1}}
Cc = {{1, 0, 0}}
Cc . Inverse[s*IdentityMatrix[3] - Ac] . Bc

Ac = {{0, 1}, {-1, -1}}

    Bc = {{0}, {1}}

    Cc = {{1, 1}}

    Together[
      Cc . Inverse[s*IdentityMatrix[2] - Ac] . Bc]

A = {{0, 1}, {-1, -1}}
ans = MatrixExp[A*t]

t = 0;
ans

t = 0.1;
ans - Sum[MatrixPower[A*t, i]/i!, {i, 0, 5}]

Clear[t]
Simplify[
      Inverse[MatrixExp[A*t]] - 
        MatrixExp[-A*t]]
Simplify[
      D[MatrixExp[A*t], t] - A . MatrixExp[A*t]]
Simplify[
      MatrixExp[A*t] - 
        InverseLaplaceTransform[Inverse[s*IdentityMatrix[2] - A], s, 
          t]]