C言語教えて解決したらアマギフ1000円

}

double discriminant(int a, int b, int c)
{
double d;
d = b * b – 4 * a * c;
return d;
}

double positiveSolution(int a, int b, int c)
{
double ps;
ps = (-1*b + sqrt(b * b – 4 * a * c)) /( 2 * a);
return ps;
}

double negativeSolution(int a, int b, int c)
{
double ns;
ns = (-1*b – sqrt(b * b – 4 * a * c)) / (2 * a);
return ns;
}