Câu 11:

Biết $\mathop {\lim }\limits_{x \to + \infty } f\left( x \right) = m;\,\,\,\mathop {\lim }\limits_{x \to + \infty } g\left( x \right) = n.$ Tính $\mathop {\lim }\limits_{x \to + \infty } \left[ {f(x) + g(x)} \right]$