Option Explicit
Dim a, b, c As Single
Private Sub cmd1_Click()
a = Val(txt1)
b = Val(txt2)
c = Val(txt3)
If (a = 0) Then
txt5 = ""
lbl5 = " "
Dim t As String
t = MsgBox("Ban can nhap du lieu truoc khi tinh", 4 + 16, "Thoâng baùo")
Else
Dim d, x1, x2 As Single
d = (b * b) - (4 * a * c)
If d < 0 Then
lbl5 = "PT voâ nghieäm"
txt5.Visible = False
lbl7(1).Visible = False
txt4.Visible = False
lbl6.Visible = False
Else
If (d = 0) Then
lbl5 = "PT coù moät nghieäm"
lbl6.Caption = "X ="
txt4 = Str(-b / (2 * a))
txt5.Visible = False
lbl7(1).Visible = False
txt4.Visible = True
lbl6.Visible = True
Else
x1 = ((-b) - Sqr(d)) / (2 * a)
x2 = ((-b) + Sqr(d)) / (2 * a)
txt4.Visible = True
lbl6.Visible = True
txt5.Visible = True
lbl7(1).Visible = True
txt4 = Str(Mid(Str(x1), 1, InStr(1, Str(x1), ".", 1) + 2))
txt5 = Str(Mid(Str(x2), 1, InStr(1, Str(x2), ".", 1) + 2))
lbl5 = "PT coù hai nghieäm"
End If
End If
End If
End Sub
Private Sub cmd2_Click()
txt1 = ""
txt2 = ""
txt3 = ""
txt1.SetFocus
End Sub
Private Sub cmd3_Click()
lbl5 = ""
txt4 = ""
txt5 = ""
End Sub
Private Sub cmd4_Click()
Dim t As String
t = MsgBox("Ban có muon thoat khong?", 4 + 16, "Thoâng baùo")
If t = vbYes Then
End
End If
End Sub