求方程[img=131x24]1803072e79d1d8e.png[/img]的数值解，结果保留20位有效数字 A: NSolve[x+x^2+x^3==30,x,20] B: NSolve[x+x^2+x^3==30,20] C: NSolve[x+x^2+x^3==30,{x,20}] D: N[Solve[x+x^2+x^3==30],20]

‏求方程[img=131x24]1803072f173bddc.png[/img]的数值解，结果保留20位有效数字‎ A: NSolve[x+x^2+x^3==30,x,20] B: NSolve[x+x^2+x^3==30,20] C: N[Solve[x+x^2+x^3==30],20] D: NSolve[x+x^2+x^3==30,{x,20}]

求解方程[img=248x27]1803072e717e3d3.png[/img]的命令是 A: Solve[(y-3)^3+(y+3)^3==9y(1-2y)] B: Solve[(y-3)^3+(y+3)^3=9y(1-2y),y] C: Solve[(y-3)^3+(y+3)^3==9y(1-2y),y] D: NSolve[(y-3)^3+(y+3)^3==9y(1-2y),y]

‏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}]