用二分法求函数f(x)=x^3-6x-1=0 在x=2~5 范围内的x=2附近的一个实根,其计算误差为|xl-x2|<10^(-6)。完善下列程序。 Private Sub Command1_Click ( ) Dim V0 As Singke, v As Single, s As String Dim x As Single, t As Single, x1 As Single, x2 As Single x1=0: x2=5 Do While _____ x = (x1+x2)/2 If Sgn(f1(x)) = 1 Then x2 = x Else x1 = x End If Loop Print "x = "; x End Sub Private Function f1(x As Single) As Single f1 = x * x * x -6 * x-1 End Function