6) Use the exponential of a matrix to solve the following systems of linear differential equations
(a) \begin{cases} \frac{dy_1}{dt} = y_1\\ \frac{dy_2}{dt} = y_1 + y_2 \end{cases} , \qquad y_1(0) = 0, y_2(0) = -3
(b) \begin{cases} \frac{dy_1}{dt} = 4y_1 + y_2\\ \frac{dy_2}{dt} = -2y_1 + y_2 \end{cases} , \qquad y_1(0) = -1, y_2(0) = 2
(c) \begin{cases} \frac{dy_1}{dt} = 10y_1 - 18y_2\\ \frac{dy_2}{dt} = 6y_1 - 11y_2 \end{cases} , \qquad y_1(0) = 2, y_2(0) = 1