Question

用C语言编写程序，输入一元二次方程的系数a，b，c，计算方程的根（假设是两个实根，测试数据必须保证这一

急，拜求答案

Answer 1

希望有用，敬请采纳 ^_^

# include<stdio.h>
# include<math.h>
int main()
{
void root2(double a,double b,double disc); //定义方程有两个根时的函数
void root1(double a,double b); //定义方程只有一个根时的函数
void root0(); //定义方程没有实数解是的函数
double a,b,c,disc;
printf("请输入a,b,c的值：");
scanf("%lf %lf %lf",&a,&b,&c);
if(a==0) //一元二次方程二次项系数不为0
{
printf("data error\n");
}
else
{
disc=b*b-4*a*c;
if(disc>0)
root2(a,b,disc);
else if(disc==0)
root1(a,b);
else
root0();
}
return 0;
}
void root2(double a,double b,double disc)
{
double x1,x2;
x1=(-b+sqrt(disc))/(2*a);
x2=(-b-sqrt(disc))/(2*a);
printf("x1=%lf\nx2=%f\n",x1,x2);
}
void root1(double a,double b)
{
double x;
x=(-b)/(2*a);
printf("x1=x2=%lf\n",x);
}
void root0()
{
printf("方程没有实数解\n");
}

Answer 2

package chapter02;

import java.util.Scanner;

class 一元二次方程 {
public static void main(String[]args) {
Scanner sc = new Scanner (System.in);
System.out.println("输入1次方的系数");
int a=sc.nextInt();
System.out.println("输入1次方的系数");
int b=sc.nextInt();
System.out.println("输入0次方的系数");
int c=sc.nextInt();
double x1=(-b+Math.sqrt(b*b-4*a*c))/2*a;
double x2=(-b-Math.sqrt(b*b-4*a*c))/2*a;
System.out.println("根分别是"+x1+","+x2);
}

}

Answer 3

#include<stdio.h>
#include<math.h>
void main()
{
float a,b,c,x,x1,x2;
printf("input a b c");
scanf("%f%f%f",&a,&b,&c);
x=sqrt(b^2-4*a*c);
printf("x1,x2");
printf("%f %f",(-b+x)/(2*a),(-b-x)/(2*a));
}