mathematica解方程组Solve[{(\[Pi] r^2)/3 + (a*\[Pi] r x)/Sqrt[r^2 + x^2] == 0, 4 a*\[Pi] R + 2 \[Pi] R^2 + (2 a*\[Pi] R^2)/ Sqrt[-r^2 + R^2] + (\[Pi] R (r^2/3 + (2 R^2)/3))/ Sqrt[-r^2 + R^2] + 2 \[Pi] *a*Sqrt[-r^2 + R^2] + 4/3 \[Pi] R

mathematica解方程组
Solve[{(\[Pi] r^2)/3 + (a*\[Pi] r x)/Sqrt[r^2 + x^2] == 0, 
  4 a*\[Pi] R + 2 \[Pi] R^2 + (2 a*\[Pi] R^2)/
    Sqrt[-r^2 + R^2] + (\[Pi] R (r^2/3 + (2 R^2)/3))/
    Sqrt[-r^2 + R^2] + 2 \[Pi] *a*Sqrt[-r^2 + R^2] + 
    4/3 \[Pi] R Sqrt[-r^2 + R^2] == 
   0,-((2 *a*\[Pi] r R)/
     Sqrt[-r^2 + R^2]) - (\[Pi] r (r^2/3 + (2 R^2)/3))/
    Sqrt[-r^2 + R^2] + 2/3 \[Pi] r Sqrt[-r^2 + R^2] + (2 \[Pi] r x)/
    3 + (a*\[Pi] r^2)/Sqrt[r^2 + x^2] + \[Pi] *a Sqrt[r^2 + x^2] == 
   0,\[Pi] r Sqrt[r^2 + x^2] + 2 \[Pi] R^2 + 
    2 \[Pi] R Sqrt[-r^2 + R^2] == S},{R,r,x,a}]

mathmatica为什么解不出来?

你Solve的格式写的不对方程组之间要用&&连接,Solve的帮助里第二个就是方程组的例子