1.
limn(n2(n2+1)(n+1)+n2(n2+4)(n+2)++n2(n2+n2)(n+n))\lim_{n\to\infty}(\frac{n^2}{(n^2+1)(n+1)}+\frac{n^2}{(n^2+4)(n+2)}+\cdots+\frac{n^2}{(n^2+n^2)(n+n)}) is equal to