Imports System.Math
Public Class Form1

    Dim stupanj As Integer = 0
    Dim vrijednost As Double = 0

    Private Sub stupanj_tbox_TextChanged(sender As Object, e As EventArgs) Handles stupanj_tbox.TextChanged
        stupanj = stupanj_tbox.Text
        koef_listbox.Items.Clear()
        koef_label.Text = "Koeficijent a" & koef_listbox.Items.Count
        vrijednost_listbox.Items.Clear()
    End Sub

    Private Sub upisi_button_Click(sender As Object, e As EventArgs) Handles upisi_button.Click
        If koef_listbox.Items.Count <= stupanj Then
            koef_listbox.Items.Add(CInt(koef_tbox.Text))
            koef_tbox.Text = ""
            koef_tbox.Focus()

            koef_label.Text = "Koeficijent a" & koef_listbox.Items.Count
        Else
            For x As Integer = -5 To 5
                For k As Integer = 0 To stupanj
                    vrijednost += koef_listbox.Items(k) * Pow(x, k)
                Next
                vrijednost_listbox.Items.Add(vrijednost)
                vrijednost = 0
            Next
        End If
    End Sub
End Class