Public Class Form1

    Function mvvod(ByVal t As TextBox)
        Return Val(t.Text)
    End Function

    Function sa(ByVal x As Double)
        Return (x ^ 3 - 6 * x ^ 2 + 19.8)
    End Function

    Sub vivodlist(ByVal x As Double, ByVal l As ListBox)
        l.Items.Add(Format(x, "00.0000"))
    End Sub

    Sub vivod(ByVal x As Double, ByVal t As TextBox)
        t.Text = CStr(x)
    End Sub

    Sub tes(ByVal a As Double, ByVal b As Double, ByVal h As Double, ByRef pro As Double)
        Dim x, y, n As Double

        n = Fix((b - a) / h) + 1
        x = a
        pro = 1

        For i = 1 To n
            y = sa(x)
            If (y > 1.2) Then
                pro = pro * y
            End If

            vivodlist(x, ListBox1)
            vivodlist(y, ListBox2)
            x = x + h

        Next
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim a, b, h, pro As Double

        a = mvvod(TextBox4)
        b = mvvod(TextBox5)
        h = mvvod(TextBox6)

        tes(a, b, h, pro)

        vivod(pro, TextBox7)


    End Sub
End Class