急求，用牛顿迭代法求方程，用VB解

Dim a, b Private Sub Command1_Click() temp = (Val(a) + Val(b)) / 2 If h(temp) = Abs(h(temp)) And h(a) < 0 Then b = temp If h(temp) = Abs(h(temp)) And h(b) < 0 Then a = temp If h(temp) Abs(h(temp)) And h(a) > 0 Then b = temp If h(te