设A={(x,y)▏x-2y=1},B={(x,y)▏x+2y=3},求AB
A: (2,0.5)
B: {(2,0.5)}
C: {2,0.5}
D: [2,0.5]
A: (2,0.5)
B: {(2,0.5)}
C: {2,0.5}
D: [2,0.5]
举一反三
- 在使用surf绘制空间曲面时,需要先生成网格点矩阵。若绘图区域为-2<x<2,-3<y<3,曲面方程为z=3*x*y^2,下列指令正确的是( ) A: x=-2:0.5:2; y=-3:0.5:3; z=3*x.*y.^2; surf(x,y,z) B: x=-2:0.5:2; y=-3:0.5:3; [x,y]=meshgrid(x,y); z=3*x.*y.^2; surf(x,y,z) C: x=-2:0.5:2; y=-3:0.5:3; z=3*x*y^2; surf(x,y,z) D: x=-2:0.5:2; y=-3:0.5:3; z=3*x.*y^2; surf(x,y,z)
- 假设X服从二项分布B(2,0.5),则D(X)= A: 1 B: 2 C: 0.5 D: 0.1
- 在环形区域[img=136x26]18030733be53638.png[/img]上, 绘制函数图形[img=129x27]18030733c6c9cd6.png[/img] A: Plot3D[x^2+y^2,{x,-2,2},{y,-2,2},Exclusions→Function[{x,y},0.5<x^2+y^2<2]] B: Plot3D[x^2+y^2,{x,-2,2},{y,-2,2},RegionFunction→Function[{x,y},0.5<x^2+y^2<2]] C: Plot3D[x^2+y^2,{x,-2,2},{y,-2,2},RegionFunction→Function[{x,y},2>x^2+y^2>0.5]] D: Plot3D[x^2+y^2,{y,-2,2},{x,-2,2},Exclusions→Function[{x,y},0.5<x^2+y^2<2]]
- 设随机变量X和Y的相关系数为0.5,E(X)=E(Y)=0,D(X)=D(Y)=2,则EXY=( ) A: 1 B: 2 C: 0.5 D: 4
- 设有浮点数x=0.5(10进制),y=-0.4375(十进制),求x*y(二进制数表示) A: -1.111*2^-1 B: -1.110*2^-3 C: -1.011*2^-1 D: -1.111*2^-3