Question

c++做，从键盘上输入a，b，c，计算并输出一元二次方程：ax2+bx+c=0的解。

要计算机考试了，希望高手帮帮忙。。。不胜感激。。。
我是初学者，希望用简单的代码。。。

Answer 1

#include<iostream.h>
#include<math.h>

void main()
{
double a,b,c,m,x1,x2;

cout<<"a=";

cin>>a;

cout<<"b=";

cin>>b;

cout<<"c=";

cin>>c;

m=b*b-4*a*c;

if(m>=0)

{ x1=(-b-sqrt(m))/2;
x2=(-b+sqrt(m))/2;
cout<<"x1="<<x1<<endl;
cout<<"x2="<<x2<<endl; }
else
cout<<"无解"<<endl;
}

Answer 2

void main()
{
int xx;
int a,b,c;
cout<<"a=";
cin>>a;
cout<<"b=";
cin>>b;
cout<<"c=";
cin>>c;
xx=b*b-4*a*c;
if (xx>0)
{
cout<<"x1="<<(-b+sqrt(xx))/2.0<<endl;
cout<<"x2="<<(-b-sqrt(xx))/2.0<<endl;
}
else if (xx<0)
{
cout<<"x1="<<-b/2.0<<"+"<<sqrt(-xx)/2.0<<"i"<<endl;
cout<<"x2="<<-b/2.0<<"-"<<sqrt(-xx)/2.0<<"i"<<endl;
}
else
{
cout<<"x1=x2="<<-b/2.0<<endl;
}
}

Answer 3

#include <stdio.h>
#include <iostream.h>
#include <math.h>
void main()
{

double a,b,c;
cout<<"Please enter a number:";
cin>>a;
cout<<"Please enter b number:";
cin>>b;
cout<<"Please enter c number:";
cin>>c;
if ((b*b-4*a*c)>0)
{
cout<<"x1="<<(-b+sqrt((b*b-4*a*c))/(2*a))<<endl;
cout<<"x2="<<(-b-sqrt((b*b-4*a*c))/(2*a))<<endl;
}
else
cout<<"number error!"<<endl;
}

}

Answer 4

#include<iostream.h>
#include<math.h>
void
main()
{
double
a,b,c,m,x1,x2;
cout<<"a=";
cin>>a;
cout<<"b=";
cin>>b;
cout<<"c=";
cin>>c;
m=b*b-4*a*c;
if(m>=0)
{
x1=(-b-sqrt(m))/2;
x2=(-b+sqrt(m))/2;
cout<<"x1="<<x1<<endl;
cout<<"x2="<<x2<<endl;
}
else
cout<<"无解"<<endl;
}