I've been given this problem: for differential equation \begin{align} y'=-25y \end{align} consider these two Runge-Kutta methods: a) midpoint b) Heun's Choose whichever is more absolute stable, determine maximal step so that method wouldnt oscilate due to being unstable.
Now from course of calculus I know how to precisely solve this having a general solution of $y(x)=\exp(-25x+c)$ /or for convenience define $d:=\exp(c)$ then $y(x)=d*\exp(-25x)$ / or particular given a initial entry/condition (something like $y(0)=1$). However I do not understand how am I to proceed in this particular case as I'm unable to continue without initial condition. I know the matrices for both of these methods but am unable to continue due to lack of comprehension.