求高手帮帮忙做一个绘制一元二次函数图形的程序，非常感谢！！！

又來～
先自己搞出一個一元二次因式分解的公式～把公式用For循環解出X值解～
再用MSChart控件空件繪製出圖形即可～

更正～一元二次方程式只有两个X值解～怎画图？
x=(-b+√b^2-4ac/2a) and x=(-b-√b^2-4ac/2a)
两点图吗？

http://siro.moe.edu.tw/teach/index.php?n=0&m=0&cmd=content&sb=3&v=3&p=437
想不到这是国中程度的问题～

Private Sub Form_Load()
Dim i As Long, j As Long, k As Long, m As Long

    'y = ax^2+bx+c    'Sample Function
    
    Do While i < 3    '依序輸入a，b，c的值～～若輸入錯誤則該項會一直跳出～直到正確輸入為止～
        a = Val(InputBox("", "第 " & i + 1 & " 個字"))
        If a <> 0 Then
            ReDim Preserve Conster(i)
            Conster(i) = a
            i = i + 1
        End If
    Loop
    
    If Conster(0) <> 0 And Conster(1) <> 0 Then
    
        a = Conster(0)    '通過驗證後開始賦值～
        b = Conster(1)
        c = Conster(2)
        
        'x=(-b+√b^2-4ac/2a) and x=(-b-√b^2-4ac/2a)   再来算X值     

    End If

[ 本帖最后由 wube 于 2011-6-8 13:59 编辑 ]

网路现成的方程求解代码～参考看看～

//方程
#include<cmath>//定义sqrt()函数
#include<iostream>
using namespace std;
int main()
{
    float a,b,c;
    cout<<"Enter the coefficients of a quadratic equation:"<<endl;
    cin>>a>>b>>c;
    if (fabs(a)<=1e-6) 
    {
        cout<<"This is not a quadratic equation: a==0\n";
        return 0;
    }
    else
        cout<<"The equation is:"<<a<<"*x*x+"<<b<<"*x+"<<c<<"=0"<<endl;

 
    double d=b*b-4*a*c;//判别式
    
    if (fabs(d)<=1e-6) 
    {
        cout<<"This equation has no real solutions: d<0\n";
        return 0;
    }
    else
       //double sqrtd=sqrt(d);
       double x1=(-b+sqrt(d))/(2*a);
       double x2=(-b-sqrt(d))/(2*a);
       cout<<"The solution are:"<<endl;
       cout<<"x1="<<x1<<endl;
       cout<<"x2="<<x2<<endl;
       cout<<"check:"<<endl;
       cout<<"\ta*x1*x1+b*x1+c="<<a*x1*x1+b*x1+c<<endl;
       cout<<"\ta*x2*x2+b*x2+c="<<a*x2*x2+b*x2+c<<endl;
       return 0;
}