Option Explicit
Dim x As Double
Dim y As Double
Dim eps As Double
Dim dx As Double
Dim dy As Double
Dim a1 As Double
Dim a2 As Double
Dim b1 As Double
Dim b2 As Double
Dim c1 As Double
Dim c2 As Double
Dim n As Double


Function F1(x As Double, y As Double) As Double
F1 = 'первая функция
End Function

Function F2(x As Double, y As Double) As Double
F2 = 'вторая функция
End Function

Function dF1dx(x As Double, y As Double) As Double
dF1dx = 'частная производная по X первой функции
End Function

Function dF2dx(x As Double, y As Double) As Double
dF2dx = 'частная производная по X второй функции
End Function

Function dF1dy(x As Double, y As Double) As Double
dF1dy = 'частная производная по Y первой функции
End Function

Function dF2dy(x As Double, y As Double) As Double
dF2dy = 'частная производная по Y второй функции
End Function

Sub Calculate()
a1 = dF1dx(x, y)
a2 = dF2dx(x, y)
b1 = dF1dy(x, y)
b2 = dF2dy(x, y)
c1 = -F1(x, y)
c2 = -F2(x, y)
dx = (b2 * c1 - b1 * c2) / (a1 * b2 - a2 * b1)
dy = (a1 * c2 - a2 * c1) / (a1 * b2 - a2 * b1)
End Sub

Private Sub Command1_Click()
x = InputBox("x")
y = InputBox("y")
eps = InputBox("eps")
n = 0
Do
n = n + 1
If n = 1000 Then Exit Do
Calculate
x = x + dx
y = y + dy
Loop Until Sqr(dx * dx + dy * dy) <= eps
Print "Получено решение:"
Print "x = "; x
Print "y = "; y
Print "F1(x,y) = "; F1(x, y)
Print "F2(x,y) = "; F2(x, y)
Print "Число итераций n="; n
End Sub