C :

#include "stdio.h"
#include "math.h"
int main() {
    float a = 2, b = 3, c = 1;
    scanf("%f,%f,%f", &a, &b, &c);
    if ((b * b - 4 * a * c) < 0) {
        printf("error!\n");
        return 0;
    }
    float x1 = (-b + sqrt(b * b - 4 * a * c)) / (2 * a);
    float x2 = (-b - sqrt(b * b - 4 * a * c)) / (2 * a);
 
    printf("x1=%7.4f, x2=%7.4f\n", x1, x2);
 
    return 0;
}