原式=∫(0,1)dx∫(√x,2√x)(x^2+y^2)dy=∫(0,1)dx*[x^2*y+(1/3)*y^3]|(√x,2√x)=∫(0,1)[x^(5/2)+(7/3)*x^(3/2)]dx=[(2/7)*x^(7/2)+(14/15)*x^(5/2)]|(0,1)=128/105
