∫(上限-1，下限-2) (1+1/x)^2 dx=∫(上限-1，下限-2) 1+ 2/x +1/x^2 dx= x +2ln|x| -1/x 代入上下限-1，-2= (-1+2ln1 +1) - (-2+2ln2 +1/2)= 3/2 -2ln2
