Question

编写程序：输入a,b,c三个数，求一元二次方程ax^2+bx+c=0的根

Answer 1

#include<stdiio.h>
#include<math.h>/*开方函数*/
main()
{
float a,b,c,x1,x2;
scanf("%f %f %f",&a,&b,&c);
x1=(-b+sqrt(b*b-4*a*c))/(2*a);
x2=(-b-sqrt(b*b-4*a*c))/(2*a);
printf("%f,%f",x1,x2);
}

Answer 2

请参考

Answer 3

#include<iostream>
using namespace std;
bool HasD(double a,double b,double c);
double D(double a,double b,double c);
int main()
{
double a,b,c;
double Delta;
cin>>a>>b>>c;
if(!HasD(a,b,c)) cout<<"没"<<endl;
if(HasD(a,b,c))
{
Delta=D(a,b,c);
cout<<"X1=\t"<<(sqrt(Delta)-b)/(2*a)<<endl;
cout<<"X2=\t"<<(-sqrt(Delta)-b)/(2*a)<<endl;
}
return 0;
}

bool HasD(double a,double b,double c)
{
return (b*b-4*a*c>0?1:0);
}

double D(double a,double b,double c)
{
return b*b-4*a*c;
}

Answer 4

还应该考虑a有时候会为0的情况？