[函数] #include＜stdio.h＞ #include＜stdlib.h＞ #include＜math.h＞ Main() { float a,b,c,delta,x1,x2; printf("Enter a,b,c"); scanf("%f%f%f",&a,&b,&c)); if(______) if(______) printf("Input error!\n"); else printf("The single root is %f\n",______); else { delta=b*b-4*a*c; if(______) { x1=(-b+sqrt(delta))/(2*a); x2=(-b-sqrt(delta))/(2*a); printf("x1=%8.2f\nx2=%8.2f\n",x1,x2,); } else if(delta==0) printf("x1=x2=%8.2f\n",______); else { Printf("z2=%8.2f+%8.2f*i\n",-b/(2*a),sqrt(-delta)/)(2*abs(a))); Printf("z2=%8.2f-%8.2f*i\n",-b/(2*a),sqrt(-delta)/(2*abs(a))); } } }

在代码中，if语句中的第一个条件应该是a==0，第二个条件应该是c==0，单根的输出应该为-x2/(2*a)，delta为0时单根和两根相等的输出应该为-x1/(2*a)。修改后的代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main() {
    float a, b, c, delta, x1, x2;
    printf("Enter a, b, c: ");
    scanf("%f%f%f", &a, &b, &c);
    if (a == 0) {
        printf("Input error!\n");
    } else if (c == 0) {
        x1 = 0;
        x2 = -b / a;
        printf("x1 = %8.2f\nx2 = %8.2f\n", x1, x2);
    } else {
        delta = b * b - 4 * a * c;
        if (delta > 0) {
            x1 = (-b + sqrt(delta)) / (2 * a);
            x2 = (-b - sqrt(delta)) / (2 * a);
            printf("x1 = %8.2f\nx2 = %8.2f\n", x1, x2);
        } else if (delta == 0) {
            x1 = x2 = -b / (2 * a);
            printf("x1 = x2 = %8.2f\n", x1);
        } else {
            printf("z1 = %8.2f + %8.2fi\n", -b / (2 * a), sqrt(-delta) / (2 * abs(a)));
            printf("z2 = %8.2f - %8.2fi\n", -b / (2 * a), sqrt(-delta) / (2 * abs(a)));
        }
    }
    return 0;
}