  The Eulerian and Lagrangian second-order perturbation theories are solved
explicitly in closed forms in $\Omega \neq 1$ and $\Lambda \neq 0$
{}Friedmann-Lema\^{\i}tre models. I explicitly write the second-order theories
in terms of closed one-dimensional integrals. In cosmologically interested
cases ($\Lambda = 0$ or $\Omega + \lambda = 1$), they reduce to elementary
functions or hypergeometric functions. For arbitrary $\Omega$ and $\Lambda$, I
present accurate fitting formula which are sufficient in practice for the
observational cosmology. It is reconfirmed for generic $\Omega$ and $\Lambda$
of interest that second-order effect only weakly depends on these parameters.
