【c语言|Python】求一元二次方程ax^2+bx+c=0的根

落日映苍穹つ 2023-07-19 10:32 80阅读 0赞

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNjY2MTQy_size_16_color_FFFFFF_t_70]

#include<stdio.h>
    #include<math.h>
    #define EON 1e-6//为数字“1” 
    int main(void)
    { 
    	float a,b,c;
    	double mate1,mate2,t1,t2,t3;
    	printf("plaese input three numbers:");
    	scanf("%f,%f,%f",&a,&b,&c);
    	if(fabs(a)<=EON)
    		if(fabs(b)<=EON)
    			printf("方程无解");
    		else
    			printf("方程为一元一次方程，有一个根x=%.4f\n",-c/b);
    	else
    	{ 
    		mate1=b*b-4*a*c;
    		mate2=4*a*c-b*b;
    		t1=-b/(2*a);
    		t2=sqrt(fabs(mate1))/(2*a);//在判断之前防止根号里面数小于0
    		t3=sqrt(fabs(mate2))/(2*a);
    		
    		if(mate1>EON)//相当于a>0
    		{ 
    			printf("方程有两个实根：\n");
    			printf("x1=%.4f,x2=%.4f",t1+t2,t1-t2); 
    		}
    		else if(fabs(mate1)<EON)//相当于a=0
    		{ 
    			printf("方程有一个实根：\n");
    			printf("x=%.4f",t1);
    		}
    		else
    		{ 
    			printf("方程有两个虚根：\n");
    			printf("x1=%.4f+%.4fi,x2=%.4f-%.4fi",t1,t3,t1,t3);
    		}
    	} 
    }

import math
    EON=float(0.000001)
    a=float(input('输入数字a：'))
    b=float(input('输入数字b：'))
    c=float(input('输入数字c：'))
    if(math.fabs(a)<=EON):
        if(math.fabs(b)<=EON):
            print('方程无解')
        else:
            print("{0}{1}={2:.4f}".format("方程为一元一次方程，有一个根","x",-c/b),end='\n')
            
    else:
        mate1=b*b-4*a*c
        mate2=4*a*c-b*b
        t1=-b/(2*a)
        t2=math.sqrt(math.fabs(mate1))/(2*a)
        t3=math.sqrt(math.fabs(mate2))/(2*a)
    
        if(mate1>EON):
            print("{0}".format("方程有两个实根"),end='\n')
            print("{0}={1:.4f},{2}={3:.4f}".format("x1",t1+t2,"x2",t1-t2))
        elif math.fabs(mate1)<EON:
            print('{0}'.format("方程有一个实根"),end='\n')
            print("{0}={1:.4f}".format("x",t1))
        else:
            print('{0}'.format("方程有两个虚根"),end='\n')
            print('{0}={1:.4f}+{2:.4f}{3},{4}={5:.4f}-{6:.4f}{7}'.format("x1",t1,t3,"i","x2",t1,t3,"i"))

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNjY2MTQy_size_16_color_FFFFFF_t_70_pic_center]

![在这里插入图片描述][20200330144245969.png]  
![在这里插入图片描述][20200330144308730.png]  
![在这里插入图片描述][20200330144411826.png]

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[20200330144245969.png]: /images/20230528/d99420a920a34a97a1d0759c5b9954b8.png
[20200330144308730.png]: /images/20230528/918bc7decf874c88bdee0a68f6c6566c.png
[20200330144411826.png]: /images/20230528/24a83a59c2d44a71b8336e1a87efd249.png