How do I integrate [math] {\frac {\rm d} {{\rm d} t}} u \left (t \right) =-2\,u \left (t \right) [/math] using the separable variables method?
How do I integrate [math]{\frac {\rm d} {{\rm d} t}} u \left (t \right) =-2\,u \left (t \right)[/math]?