答：
原式
=limn->+∞ n*ln[(n+2)/n]
=limn->+∞ n*ln(1+2/n)
limn->+∞ ln[(1+1/(n/2))^n]
=limn->+∞ ln[(1+1/(n/2))^(n/2)*(n/(n/2))]
=limn->+∞ ln(e^2)
=2