原式=∫(0,1)ln(x+1)d(x+1)=(x+1)ln(x+1) (0,1)-∫(0,1)(x+1)dln(x+1)=(x+1)ln(x+1) (0,1)-∫(0,1)(x+1)*1/ln(x+1) dx=(x+1)ln(x+1) (0,1)-∫(0,1) dx=[(x+1)ln(x+1)-x] (0,1)=2ln2-1
