Dim x1, x2
Private Function f(a, b, fun) 'x()初值,目标函数多项式
   x1 = a
   x2 = b
   f = fun
End Function

Private Sub Command1_Click()
   Label1.Caption = f(2, 2, x1 ^ 2 + 2 * x1 * x2 + x2 ^ 2)
End Sub