syms x y f=x^2+y^2 g=int(f,y,0,1-x)r=int(g,x,0,2)输出：f = x^2 + y^2 g = - x^2*(x - 1) - (x - 1)^3/3 r = -4/3
f = int(int(X*X+Y, Y, 2, 4), X, 1, X2);x2 = solve(f-5);x2 = vpa(x2)