Systems of Differential Equations So far,we have studied the differential equation that in- volves an unknown function and derivatives of this function. 4日0,1无2000 Linear of Differential EquationsSystems of Differential Equations So far, we have studied the differential equation that in￾volves an unknown function and derivatives of this function. In this chapter we shall deal with sets of simultaneous equations that involve several unknown functions and their derivatives. Example    d 2 x1 dt 2 −2 dx1 dt − dx2 dt = −3e 3t , dx2 dt −6x1 = 0. Linear Systems of Differential Equations