Private Sub Command1_Click()

Text1.Text = " "

Text2.Text = " "

Text3.Text = " "

Text1.SetFocus

End Sub

Private Sub Command2_Click()

Dim a, b, c, d As Double

Dim x1, x2 As String

a = Val(Text1.Text)

b = Val(Text2.Text)

c = Val(Text3.Text)

If (a = 0) Then

Text4 = (-c / b)

Text5 = ""

lbl5 = ""

Else

d = (b * b) - (4 * a * c)

If d < 0 Then

lbl5 = "PT vo nghiem"

Text4 = ""

Text5 = ""

Else

If (d = 0) Then

lbl5 = "PT co mot nghiem"

Text4 = Str(-b / (2 * a))

Text5 = " "

Else

x1 = ((-b) - Sqr(d)) / (2 * a)

x2 = ((-b) + Sqr(d)) / (2 * a)

Text4.Text = Format(x1, "0.00")

Text5.Text = Format(x2, "0.00")

lbl5 = "PT co hai nghiem"

End If

End If

End If

End Sub

Private Sub Command3_Click()

If MsgBox("Ban muon thoat ko?", vbYesNo + vbQuestion + vbDefaultButton1, "Thong bao") = vbYes Then

End

End If

End Sub

Private Sub Command4_Click()

lbl5 = " "

Text4 = " "

Text5 = " "

End Sub