>>99　>>102
↓　１行目訂正です。
Ｖ=8∫[0→a] 〔{a^(2/3)-y^(2/3)}^(3/2)〕^2 dy=8∫[0→a] {a^(2/3)-y^(2/3)}^3dy
=8∫[0→a]{a^2-3a^(4/3)y^(2/3)+3a^(2/3)y^(4/3)-y^2}dy
=8{a^2y-(9/5)a^(4/3)y^(5/3)+(9/7)a^(2/3)y^(7/3)-(1/3)y^3}_[0→a]
=8(105-189+135-35)a^3/105
=128a^3/105