Use simulation with antithetic variables and find $$\int_{-\infty}^{\infty} \int_0^\infty\, sin(x+y)e^{x^2+4x-y}\,dx\,dy,$$ so, my question and doubt is how struggle with the infinite limit ? It is easy to me this problem $\int_0^1e^x\,dx$ or similar, but do not know how the previous. Help me please.