VB解一元二次方程配方法源碼

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1、文檔供參考，可復(fù)制、編制，期待您的好評與關(guān)注！ VB解一元二次方程配方法 我也是一個vb的超級菜鳥，但是我運用我所學(xué)的數(shù)學(xué)知識，編輯了一個解一元二次方程的配方法過程的這么一個程序。我是自己原創(chuàng)，至于是不是首創(chuàng)就不知道了。(很多網(wǎng)上直接出答案的都是運用公式法計算的，那么我就想寫個有過程的程序，完爆數(shù)學(xué)老師) 好了，廢話不說多，現(xiàn)在先上測試圖，有圖有真相嘛。 這個程序有幾個重點（后面源碼都有注釋） 1、 a值要變?yōu)檎龜?shù)，否則將無法運行 2、 開不盡的數(shù)要用根號表示，不會像√2=1.414……這么多小數(shù) 3、 分母有理化，倒數(shù)第二步的分母不能為根號（標(biāo)準(zhǔn)

2、） 4、 移項時的符號注意變化。 下面是界面介紹： 下面直接上源碼了，有注釋自己可以理解。 Dim a$ ,b$,c$,d$,e$,f$,g$,h$ Dim jj! Dim ii! Dim pp! Private Sub Command1_Click() a = Text1.Text b = Text2.Text c = Text3.Text d = Text4.Text If a = 1 Then '第一步，先列出原式 Label3.Caption = "x^2" End If If a = -1

3、 Then Label3.Caption = "-x^2" End If If Not a = 1 And Not a = -1 Then Label3.Caption = a & "x^2" End If If b > 0 Then Label3.Caption = Label3.Caption & "+" & b Else Label3.Caption = Label3.Caption & b End If If c > 0 Then Label3.Caption = Label3.Caption & "x+" & c & "=" & d Else Label3

4、.Caption = Label3.Caption & "x" & c & "=" & d End If If a < 0 Then '當(dāng)a為負(fù)數(shù)時，每個項同時乘以-1 a = -a b = -b c = -c d = -d End If c = c - d '移項，將右邊移向左邊 If a = 0 Then '判斷有無解 Label3.Caption = Label3.Caption & vbCrLf & "原方程無解" End If If (b ^ 2) - (4 * a * c) < 0 Then Label3.Caption = Label3.

5、Caption & vbCrLf & "原方程無解" End If If a = 1 Then '第二步，寫出移項后的結(jié)果 Label3.Caption = Label3.Caption & vbCrLf & "x^2" End If If a = -1 Then Label3.Caption = Label3.Caption & vbCrLf & "-x^2" End If If Not a = 1 And Not a = -1 Then Label3.Caption = Label3.Caption & vbCrLf & a & "x^2" End If If b

6、 > 0 Then Label3.Caption = Label3.Caption & "+" & b Else Label3.Caption = Label3.Caption & b End If If c > 0 Then Label3.Caption = Label3.Caption & "x+" & c & "=0" Else Label3.Caption = Label3.Caption & "x" & c & "=0" End If e = (b ^ 2) / (4 * a) '算出適合配方的新c值 f = e - c '新c值與原c值的差，兩邊同時加差值

7、 If a = 1 Then '第三步，寫出初步配方的結(jié)果 Label3.Caption = Label3.Caption & vbCrLf & "x^2" End If If a = -1 Then Label3.Caption = Label3.Caption & vbCrLf & "-x^2" End If If Not a = 1 And Not a = -1 Then Label3.Caption = Label3.Caption & vbCrLf & a & "x^2" End If If b > 0 Then Label3.Caption = Label

8、3.Caption & "+" & b Else Label3.Caption = Label3.Caption & b End If If e > 0 Then Label3.Caption = Label3.Caption & "x+" & e & "=" & f Else Label3.Caption = Label3.Caption & "x" & e & "=" & f End If g = (-b + Sqr(b ^ 2 - 4 * a * c)) / (2 * a) '后臺使用公式法計算 h = (-b - Sqr(b ^ 2 - 4 * a * c))

9、/ (2 * a) If g > 0 And g < 1 Then '給0 < y < 1的數(shù)前加個0 g = "0" & g End If If g < 0 And g > -1 Then g = -g g = "-0" & g End If If h > 0 And h < 1 Then h = "0" & h End If If h < 0 And h > -1 Then h = -h h = "-0" & h End If jj = Sqr(a) If a = 1 Then '第四步，運用完全平方公式進(jìn)行配方 Label3.Caption = La

10、bel3.Caption & vbCrLf & "（x" End If If a = -1 Then Label3.Caption = Label3.Caption & vbCrLf & "（-x" End If If Not a = 1 And Not a = -1 Then If Not Len(CStr(jj - Fix(jj))) > 4 Then Label3.Caption = Label3.Caption & vbCrLf & "（" & Sqr(a) & "x" End If If Len(CStr(jj - Fix(jj))) > 4 Then’小數(shù)大于3位

11、時用根號表示，不直接開方 Label3.Caption = Label3.Caption & vbCrLf & "（√" & a & "x" End If End If '------------------第一層----------------------------- ii = Sqr(e) If b > 0 Then If Not Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "+" & Sqr(e) & "）^2=" & f End If If Len(CStr(ii - Fix

12、(ii))) > 4 Then Label3.Caption = Label3.Caption & "+" & "√" & e & "）^2=" & f End If End If If b < 0 Then If Not Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "-" & Sqr(e) & "）^2=" & f End If If Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "-" & "√"

13、 & e & "）^2=" & f End If End If '------------------第二層---------------------------- If a = 1 Then '第五步，兩邊同時開根號 Label3.Caption = Label3.Caption & vbCrLf & "x" End If If a = -1 Then Label3.Caption = Label3.Caption & vbCrLf & "-x" End If If Not a = 1 And Not a = -1 Then If Not Len(CStr(jj -

14、 Fix(jj))) > 4 Then Label3.Caption = Label3.Caption & vbCrLf & "" & Sqr(a) & "x" End If If Len(CStr(jj - Fix(jj))) > 4 Then Label3.Caption = Label3.Caption & vbCrLf & "√" & a & "x" End If End If If b > 0 Then If Not Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "+" & Sq

15、r(e) & "=" End If If Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "+" & "√" & e & "=" End If End If If b < 0 Then If Not Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "-" & Sqr(e) & "=" End If If Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption =

16、Label3.Caption & "-" & "√" & e & "=" End If End If pp = Sqr(f) If Not Len(CStr(pp - Fix(pp))) > 4 Then Label3.Caption = Label3.Caption & "±" & Sqr(f) End If If Len(CStr(pp - Fix(pp))) > 4 Then Label3.Caption = Label3.Caption & "±√" & f End If Label3.Caption = Label3.Caption & vbCrLf & "x

17、=" '第六步，移項，x在左 If Len(CStr(jj - Fix(jj))) > 4 Then '分母有理化(后補分母) Label3.Caption = Label3.Caption & "√" & a End If If a = 1 Then If Not Len(CStr(pp - Fix(pp))) > 4 Then Label3.Caption = Label3.Caption & "±" & Sqr(f) End If If Len(CStr(pp - Fix(pp))) > 4 Then Label3.Caption = Label3.Caption &

18、"±√" & f End If If b > 0 Then If Not Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "-" & Sqr(e) End If If Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "-" & "√" & e End If End If If b < 0 Then If Not Len(CStr(ii - Fix(ii))) > 4 Then Label3.Capti

19、on = Label3.Caption & "+" & Sqr(e) End If If Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "+" & "√" & e End If End If End If '------------------------第一層--------------------------- If Not a = 1 Then If Not Len(CStr(pp - Fix(pp))) > 4 Then Label3.Caption = Label3.Capti

20、on & "（±" & Sqr(f) End If If Len(CStr(pp - Fix(pp))) > 4 Then Label3.Caption = Label3.Caption & "（±√" & f End If If b > 0 Then If Not Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "-" & Sqr(e) & "）/" End If If Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Ca

21、ption & "-" & "√" & e & "）/" End If End If If b < 0 Then If Not Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "+" & Sqr(e) & "）/" End If If Len(CStr(ii - Fix(ii))) > 4 Then Label3.Caption = Label3.Caption & "+" & "√" & e & "）/" End If End If If Not Len(CStr(jj - Fix(j

22、j))) > 4 Then Label3.Caption = Label3.Caption & Sqr(a) End If If Len(CStr(jj - Fix(jj))) > 4 Then Label3.Caption = Label3.Caption & a End If End If Label3.Caption = Label3.Caption & vbCrLf & "x=" & g & "或x=" & h '第七步，得解 End Sub Private Sub Command2_Click() Text1.Text = "" Text2.Text

23、 = "" Text3.Text = "" Text4.Text = "" Label3.Caption = "解題區(qū)域" End Sub Private Sub Command3_Click() a = Text1.Text b = Text2.Text c = Text3.Text d = Text4.Text c = c - d Label6.Visible = True Label7.Visible = True Label8.Visible = True Label9.Visible = True Line1.Visible = True Li

24、ne2.Visible = True Label5.Caption = "∵a=" & a & "，b=" & b & "，c=" & c '第一步，列出a、b、c的值（格式嚴(yán)謹(jǐn)） Label5.Caption = Label5.Caption & vbCrLf & "∴△=b^2-4ac=" & (b ^ 2) - (4 * a * c) '第二步，算出變量b^2-4ac的值 If (b ^ 2) - (4 * a * c) < 0 Then '第三步，判斷方程有無解 Label5.Caption = Label5.Caption & vbCrLf & "∴b^2-4ac <

25、 0，方程無解。" Else If b > 0 Then Label7.Caption = "-" & b & "±√" & (b ^ 2) - (4 * a * c) '第四步，寫分子 Else Label7.Caption = -b & "±√" & (b ^ 2) - (4 * a * c) End If End If Label8.Caption = 2 * a '第四步，寫分母 g = (-b + Sqr(b ^ 2 - 4 * a * c)) / (2 * a) '公式法運算 h = (-b - Sqr(b ^ 2 - 4 * a * c)) / (2 *

26、a) If g > 0 And g < 1 Then '加0 g = "0" & g End If If g < 0 And g > -1 Then g = -g g = "-0" & g End If If h > 0 And h < 1 Then h = "0" & h End If If h < 0 And h > -1 Then h = -h h = "-0" & h End If Label9.Caption = "∴x=" & g & "或x=" & h '第五步，得解 End Sub Private Sub Command4_Click() Label6.Visible = False Label7.Visible = False Label8.Visible = False Label9.Visible = False Line1.Visible = False Line2.Visible = False Label5.Caption = "解題區(qū)域" End Sub 以上有些代碼可能編的有點傻瓜，因為我也只是個菜鳥，能達(dá)到效果我就覺得可以的了。 更重要的是自己認(rèn)真的學(xué)習(xí)一元二次方程，不能依賴程序。 感謝讀者的支持。 9 / 9