Consider the system of differential equations dx/dt=−2y dy/dt=−2x.  Convert this system to a second-order differential equation in y by differentiating the second equation with respect to t and substituting for x from the first equation. Solve the equation you obtained for y as a function of t; hence find x as a function of t. If we also require x(0)=4 y(0)=3, what are x and y?
a). x(t)= 

b). y(t)=