一个初学者的思路

解题思路:

注意事项:

主要就是Δ<0时，有共轭复根，

参考代码:

#include<stdio.h>

#include<math.h>

void fun1(double a,double b,double c);

void fun2(double a,double b,double c);

void fun3(double a,double b,double c);

int main()

{

double  a,b,c;

scanf("%lf%lf%lf",&a,&b,&c);

double sum=pow(b,2)-4*a*c;

if(sum==0){

fun1(a,b,c);

}else if(sum>0){

fun2(a,b,c);

}else if(sum<0){

fun3(a,b,c);

}

return 0;

 } 

 void fun1(double a,double b,double c)

 {

  double x1=-1/(a*2);

  double x2=-1/(a*2);

  printf("x1=%.3lf x2=%.3lf",x1,x2);

 }

 void fun2(double a,double b,double c)

 {

  double count=pow(b,2)-4*a*c;

  double x1=(-b+sqrt(fabs(count)))/2/a;

  double x2=(-b-sqrt(fabs(count)))/2/a;

  printf("x1=%.3lf x2=%.3lf",x1,x2);

 }

 void fun3(double a,double b,double c)

 {

  double count=-1/(2*a);

  double s=sqrt(4*a*c-pow(b,2));

  printf("x1=%.3lf+%.3lfi x2=%.3lf-%.3lfi",count,s/2/a,count,s/2/a);

 }