Quadratic Equation (Functions)

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


double sqrt (double number) {
    double sqrtNumber = number * number;
    return sqrtNumber;
}



double discriminant(double a, double b, double c) {
   double  result = b*b - 4 * a * c;
   return result;
}

double x1(double a, double b, double D) {
  double result  = (-1 * b +sqrt(D))/2.0 * a;
}

double x2(double a, double b, double D) {
  double result  =  (b +sqrt(D))/-2.0 * a;
}

void quadr(double a, double b, double c) {
  double D = discriminant(a, b, c);
  if (D<0) {
     printf("Invalid argument");

  }
  else if (a==0) {
     printf("a should not be 0\n");
  }
  else {
   double result1 = x1(a,b,D);
   double result2 = x2(a,b,D);
   printf("x1 = %lf, x2 = %lf", result1, result2);
  }

}

int main(){

 quadr(82.06, -155.4, 69.24);
 return 0;


}