i just tried my vba code for bisection method but it doesn't work. can someone help me by telling me where i went wrong.pppleeasse

Option Explicit
'declare global variables
Dim a As Double
Dim b As Double
Dim x As Double
Dim e As Double
Dim exp As Double
Sub getinputs()
'retrieve values from the spredsheet
e = Cells(4, 3)
a = Cells(5, 3)
b = Cells(6, 3)
x = (a + b) / 2
exp = Cells(8, 3)

End Sub
Sub getroot()
Dim fX As Double
Dim fA As Double
Dim fB As Double
Dim k As Integer
Dim n As Integer
n = Cells(9, 3)
Do Until k <= n
k = Cells(10, 3)

Do Until Abs(fX) <= e
fA = 2 * (a - 2) ^ 2 - exp ^ a
fB = 2 * (b - 2) ^ 2 - exp ^ b
fX = 2 * (x - 2) ^ 2 - exp ^ x
x = Cells(2, 4)
fA = Cells(2, 5)
fB = Cells(2, 6)
fX = Cells(2, 7)
If fX * fA < 0 Then
b = x
End If
If fX * fB < 0 Then
a = x
End If
Loop
k = k + 1
Loop
End Sub