设L是从A(1,0)到B(-1,2)的线段,则曲线积分(x+y)ds等于:()
A: -2
B: 2
C: 2
D: 0
A: -2
B: 2
C: 2
D: 0
举一反三
- 设L是从点(0,0)沿y=1-|x-1|至点(2,0)的折线段,则曲线积分-ydx+rdy等于() A: 0 B: -1 C: 2 D: -2
- 随机变量(X,Y)的可能取值为(1,0), (1,2), (2,0), (2,2), 其联合分布律为P(X=1,Y=0)=0.1,P(X=1,Y=2)=0.2,P(X=2,Y=0)=0.4,P(X=2,Y=2)=b,则E(X+Y)等于
- \(设L是以点A(1,0),B(0,1),C(-1,0),D(0,-1)为顶点的正方形边界,\\则\oint_{L}\frac{ds}{|x|+|y|}=(\,)\) A: \[4\] B: \[2\] C: \[4\sqrt{2}\] D: \[2\sqrt{2}\]
- 随机变量(X,Y)的可能取值为(1,0), (1,2), (2,0), (2,2), 其联合分布律为P(X=1,Y=0)=0.1,P(X=1,Y=2)=0.2,P(X=2,Y=0)=0.4,P(X=2,Y=2)=b,则E(X+Y)等于 A: 1.7 B: 2.5 C: 2.7 D: 不确定
- 设\(f\left( {x,y,z} \right) = x{y^2} + y{z^2} + z{x^2}\),则\({f_{yz}}\left( {0,-1,0} \right) = \)( ) A: 1 B: 0 C: -1 D: 2