x^2 = y^2 + z^2 ==> ∫∫Dx dydz = πx^2∫∫∫ e^(x^3) dxdydz= ∫(0→1) e^(x^3) dx ∫∫Dx dydz= ∫(0→1) e^(x^3) * πx^2 dx= (π/3)∫(0→1) e^(x^3) d(x^3)= (π/3)e^(x^3)：0→1= (π/3)(e - 1)...x^2 = y^2 + z^2 ==> ∫∫Dx dydz = πx^2这一步是怎么来的啊Dx是一个以(y，z) = (0，0)，x为半径的圆。Dx的面积随着x变化∫∫Dx dydz = Dx的面积 = π(x)^2