Solving a system of first order ODEs

JevKus

Hi!

I am tackling a pretty simple system of rate equations:

N1' = -N1/t1 (1)
N2' = -N2/t2 + N1/t1 (2)

Immediately I can solve (1), i.e. N1 = C1 exp(-t/t1) and substitute the solution in (2). Then I can solve the equation by variation of constants. Finally, I get N2 = [t2/(t1-t2) C1 exp(t*(t1-t2)/t1*t2) + C2] exp(-t/t2) and it's different from a result I would get from Wolfram Alpha. Where did I go wrong?

Thanks!