Calculate the expression of the following Dirichlet's series: $$ \dfrac{\zeta(s-1)}{\zeta(s)} = \sum_{n=1}^{\infty} \dfrac{\varphi(n)}{n^s} $$ $$ \dfrac{\zeta(2s)}{\zeta(s)}=\sum_{n=1}^{\infty} \dfrac{\lambda(n)}{n^s} $$ and calculate the abscisse of convergence.
I have tried to use the definition of the Zeta of Riemann function but I don't know how to prove it. Moreover, I don't know how to calculate $\sigma_0$ (the abscisse of convergence). I wish you can give me some instructions to do it. Thanks so much.