An unforced linear time invariant (LTI) system is represented by $$\begin{bmatrix} x_1 \\ x_2 \end{bmatrix} = \begin{bmatrix} -1 & 0 \\ 0& -2 \end{bmatrix} \begin{bmatrix} x_1 \\ x_2 \end{bmatrix}$$ If the initial conditions are $x_1(0)= 1$ and $x_2(0)= -1$, the solution of the state equation is