※ 引述《JukeFF (JukeFF)》之铭言：
: 想请问一下 如下图https://i.imgur.com/VMGlKFW.jpg
: 我怎么算都是负数
: 先画出图之后
: 求出体积 y=根号x x=根号y
: 带人二重积分 怎么算都不对..
: 求神人解答...
x = y^2
y = x^2
交点在(x - y) = -(x - y)(x + y)
=> (x - y)(1 + x + y) = 0
=> x = 0, 1
或x^4 = y^2 = x
=> x(x - 1)(1 + x + x^2) = 0
=> x = 0, 1
S (x^2 + y)dx dy
x = √y
= S ((1/3)x^3 + xy)| dy
x = y^2
1
= S (1/3)[y√y - y^6] + [y√y - y^3] dy
0
= (8/15) - (1/21) - (1/4)
= 33/140
过程是这样
答案你字几再验算看看