#include<stdio.h>#include<math.h>int main() {float a,b,c,d,x1,x2,x3,p,q,i,w,s1,s2,s3,X2,X3;printf("请输入一元三次方程标准形式ax^3+bx^2+cx+d=0\n");printf("a b c d的值，用空格隔开\n");scanf("%f%f%f%f",&a,&b,&c,&d);p=(3*a*c-b*b)/(3*a*a);q=(27*a*a*d-9*a*b*c+2*b*b*b)/(27*a*a*a);w=-0.5;s1=-b/(3*a);if(-q/2+sqrt(q*q/4+p*p*p/27)>0) {s2=pow((-q/2+sqrt(q*q/4+p*p*p/27)),1.0/3);} else {s2=-pow(-(-q/2+sqrt(q*q/4+p*p*p/27)),1.0/3);}if(-q/2-sqrt(q*q/4+p*p*p/27)>0) {s3=pow((-q/2-sqrt(q*q/4+p*p*p/27)),1.0/3);} else {s3=-pow(-(-q/2-sqrt(q*q/4+p*p*p/27)),1.0/3);}x1=s1+s2+s3;x2=s1+w*s2+w*s3;X2=sqrt(3)/2*s2+(-sqrt(3)/2)*s3;x3=s1+w*s2+w*s3;X3=sqrt(3)/2*s3+(-sqrt(3)/2)*s2;printf("第一个解为：%f\n",x1);if(X2>0) {printf("第二个解为：%f+%f*i\n",x2,X2);} else {printf("第二个解为：%f%f*i\n",x2,X2);}if(X3>0) {printf("第三个解为：%f+%f*i\n",x3,X3);} else {printf("第三个解为：%f%f*i\n",x3,X3);}}
