Методом половинного деления найти корень уравнения

Dim x1 As Single, x2 As Single, x As Single
Const e = 0.000001
x1 = Val(InputBox("Введите x1"))
x2 = Val(InputBox("Введите x2"))
Const Pa = 1000
Const Pb = 270
Const Gt = 730
Const Ra = 100
Const Rb = 200
 
 
If (2 * Log(x1 / 100) - (x1 / 200) ^ 2) * (2 * Log(x2 / 100) - (x2 / 200) ^ 2) < 0 Then
    x = (x1 - x2) / 2
    Do While (2 * Log(x / 100) - (x / 200) ^ 2) >= e
        If (2 * Log(x / 100) - (x / 200) ^ 2) * (2 * Log(x1 / 100) - (x1 / 200) ^ 2) < 0 Then
            x2 = x
        Else
            x1 = x
        End If
        x = (x1 - x2) / 2
    Loop
End If
Print x, x1, x2

Sub Main()
Const e = 0.0001
Dim X1#, X2#, x#, f1#, f2#, fx#
X1 = InputBox("Введите x1", , 0)
f1 = F(X1)
X2 = InputBox("Введите x2", , 10)
f2 = F(X2)
If f1 * f2 > 0 Then
  MsgBox ("Функция имеет одинаковый знак на границах интервала")
  Exit Sub
End If
Do
  x = (X1 + X2) / 2
  fx = F(x)
  If f1 * fx < 0 Then
    X2 = x
    f2 = fx
  Else
    X1 = x
    f1 = fx
  End If
Loop Until Abs(X1 - X2) < e
x = (X1 + X2) / 2
MsgBox "x=" & x & vbTab & "F(x)=" & F(x)
End Sub
 
Function F(Rc As Double) As Double
'F = 2 * Log(Rc) - Rc ^ 2
F = Rc ^ 2 - 4
End Function