∫上2下1 [(x/2)-(1/x)-(1/x^2)]dx
=∫上2下1 [(x/2)-x^(-1)-x^(-2)]dx
=[(1/4)x^2-lnx+(1/x)]|
=[(1/4)2^2-ln2+1/2]-[(1/4)1^2-ln1+1]
=1/4-ln2