Chapter 25, Problem 7P

Use (a) Euler's and (b) the fourth-order RK method to solve

$\begin{array}{l}\frac{dy}{dt}=-2y+5e^{-t}\\ \frac{dz}{dt}=-\frac{y{z}^2}{2}\end{array}$

over the range $t=0\text{ to 0}\text{.4}$ using step size of $y\left(0\right)=2$ and $z\left(0\right)=4$.