Private Sub CommandButton1_Click()
Dim a, b, c, d  As Integer
Dim x1, x2 As Double
a = InputBox1("Ââåäèòå ïàðàìåòð a")
b = InputBox2("Ââåäèòå ïàðàìåòð b")
c = InputBox3("Ââåäèòå ïàðàìåòð c")
d = (b ^ 2) - 4 * a * c
 TextBox4 = "d=" & d
 Select Case d
 Case Is < 0
  TextBox4 = " ÍÅÒ ÐÅØÅÍÈß"
  Case Is = 0
  x1 = (-b) / (2 * a)
  x2 = (-b) / (2 * a)
 TextBox5 = "x1=" & x1 & "x2=" & x2
 Case Is > 0
 x1 = (-b + Sqr(d)) / (2 * a)
  x2 = (-b - Sqr(d)) / (2 * a)
 TextBox5 = "x1=" & x1 & "x2=" & x2
 End Select

End Sub