如图,V=∫(0到1)〔∫(0到1-y)(1+x+y)dx〕dy
=∫(0到1)(x+x^2/2+yx)|(0到1-y)〕dy
=∫(0到1)(3-2y-y^2)/2dy
=(3y-y^2-y^3/3〕/2|(0到1)
=5/6