99-6

'6.輸入 A, B, C，求 AX^2 + BX + C = 0 的解。
Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        '測試資料

        'Dim a = 4
        'Dim b = -5
        'Dim c = 1

        '輸入資料
        Dim a = InputBox("a=")
        Dim b = InputBox("b=")
        Dim c = InputBox("c=")
        If b ^ 2 - 4 * a * c < 0 Then
            MsgBox("無實數解")
        Else
            Dim x1 = (-b + (b ^ 2 - 4 * a * c) ^ 0.5) / (2 * a)
            Dim x2 = (-b - (b ^ 2 - 4 * a * c) ^ 0.5) / (2 * a)
            MsgBox("解為：" & x1 & "," & x2)
        End If
    End Sub
End Class