计算二重积分[img=159x48]18030731271aaff.png[/img], D 是单位圆盘[img=89x26]180307312f6708b.png[/img],应使用的语句是
A: Integrate[Sqrt[x^2+y^2 ], {x^2+y^2≤1}]
B: Integrate[Sqrt[x^2+y^2 ]Boole[x^2+y^2≤1],{x,-1,1},{y,-1,1}]
C: NIntegrate[Sqrt[x^2+y^2 ]Boole[x^2+y^2≤1],{x,-1,1},{y,-1,1}]
D: Integrate[Sqrt[x^2+y^2 ],{x^2+y^2≤1,{x,-1,1},{y,-1,1}}]
A: Integrate[Sqrt[x^2+y^2 ], {x^2+y^2≤1}]
B: Integrate[Sqrt[x^2+y^2 ]Boole[x^2+y^2≤1],{x,-1,1},{y,-1,1}]
C: NIntegrate[Sqrt[x^2+y^2 ]Boole[x^2+y^2≤1],{x,-1,1},{y,-1,1}]
D: Integrate[Sqrt[x^2+y^2 ],{x^2+y^2≤1,{x,-1,1},{y,-1,1}}]
举一反三
- 设随机变量（x,y）服从二维正态分布,概率密度为f（x,y）=(1/2pi)*exp[-1/2*(x^2+y^2)],求E(x^2+y^2)
- 求解方程组[img=218x63]1803072f0e0e849.png[/img]接近 (2,2) 的解 A: FindRoot[{x^2+y^2==5Sqrt[x^2+y^2]-4x,y==x^2},{x,2},{y,2}] B: NSolve[{x^2+y^2==5Sqrt[x^2+y^2]-4x,y==x^2},{x,2},{y,2}] C: FindRoot[{x^2+y^2==5Sqrt[x^2+y^2]-4x,y==x^2},{x,y},{2,2}] D: FindRoots[{x^2+y^2=5Sqrt[x^2+y^2]-4x,y=x^2},{x,2},{y,2}]
- 求解方程组[img=218x63]1803072e5daced1.png[/img]接近 (2,2) 的解 A: NSolve[{x^2+y^2==5Sqrt[x^2+y^2]-4x,y==x^2},{x,2},{y,2}] B: FindRoot[{x^2+y^2==5Sqrt[x^2+y^2]-4x,y==x^2},{x,2},{y,2}] C: FindRoot[{x^2+y^2==5Sqrt[x^2+y^2]-4x,y==x^2},{x,y},{2,2}] D: FindRoots[{x^2+y^2=5Sqrt[x^2+y^2]-4x,y=x^2},{x,2},{y,2}]
- 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]]
- 从圆心在原点的单位圆内部取一点，记录其坐标。则这个随机试验的样本空间可表示为 A: Ω={ (x,y) | -1<x<1, -1<y<1 } B: Ω={ (x,y) | 0<x<1, 0<y<1 } C: Ω={ (x,y) | x^2+y^2<1 } D: Ω={ (x,y) | x^2+y^2=1 }