先求出交点坐标为(2,8),
S=∫(0→2)x^3dx
=x^4/4(0→2)=4.
绕X轴V=π∫(0→2)(x^3)^2dx
=πx^7/7(0→2)
=128π/7.
绕Y轴V=π*2^2*8-π∫(0→8)*[y^(1/3)]^2dy
=32π-π(3/5)*y^(5/3)(0→8)
=32π-96π/5
=64π/5.
圆柱体体积-空心体积.
先求出交点坐标为(2,8),
S=∫(0→2)x^3dx
=x^4/4(0→2)=4.
绕X轴V=π∫(0→2)(x^3)^2dx
=πx^7/7(0→2)
=128π/7.
绕Y轴V=π*2^2*8-π∫(0→8)*[y^(1/3)]^2dy
=32π-π(3/5)*y^(5/3)(0→8)
=32π-96π/5
=64π/5.
圆柱体体积-空心体积.