Chapter 2, Problem 35RE

Consider the partially decoupled system
   $\begin{array}{l}\frac{dx}{dx}=x+2y+1\\ \frac{dy}{dt}=3y\end{array}$
(a) Derive the general solution.
(b) Find the equilibrium points of the system.
(c)Find the solution that satisfies the initial condition $\left(x_0,y_0\right)=\left(-1,3\right)$.
(d) Use HPGSystemsolver to plot the phase portrait for this system. Identify the solution curve that corresponds to the solution with initial condition $\left(x_0,y_0\right)=\left(-1,3\right)$.