f(y-x) = sin(y-x), x ≤ y ≤ 1+xf(y-x) = 0, 其它I = ∫<0, 1>sinxdx ∫sin(y-x)dy= ∫<0, 1>sinxdx [-cos(y-x)] = (1-cos1) ∫<0, 1>sinxdx = (1-cos1) [-cosx]<0, 1> = (1-cos1)^2
