Phuong trinh bac hai

78 0 0
by cuong000
by cuong000
                                        
                                                  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