Private Sub CmdSolve_Click()
    Dim a As Single, b As Single, c As Single, p As Single
    Dim x1 As Single, X2 As Single, e As Single, f As Single
    a = Val(txtA.Text)
    b = Val(txtB.Text)
    c = Val(txtC.Text)
    p = b ^ 2 - 4 * a * c
    
    If a = 0 Then
        txtRoot1.Text = "无解"
        txtRoot2.Text = "无解"
    Else
         If p >= 0 Then
            x1 = (-b + Sqr(p)) / (2 * a)
            X2 = (-b - Sqr(p)) / (2 * a)
            txtRoot1.Text = x1
            txtRoot2.Text = X2
        Else
            e = -b / (2 * a)
            f = (Sqr(-p)) / (2 * a)
            txtRoot1.Text = Str(e) & "+" & Str(f) & "i"
            txtRoot2.Text = Str(e) & "+" & Str(f) & "i"
        End If
    End If
End Sub