29.3

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

void swap(double *x1 , double *x2)
{
    double temp = *x1;
    *x1 = *x2;
    *x2 = temp;
}
double D(double a, double b,double c)
{
    return pow(b,2)-4*a*c;
}
double f1(double a,double b,double c)
{
    return pow(a,2) - 9*b*c;
}

double f2(double x)
{
    return 4*x;
}

double f3(double x1, double x2)
{
    return x2*sin(x1);
}
int main()
{
        double a, b, c, d;

        printf("Enter coefficients a, b and c: ");
        scanf("%lf %lf %lf",&a, &b, &c);

        d = D(a,b,c);


        if (d > 0)
        {
            double x1, x2;
            x1 = (-b+sqrt(d))/(2*a);
            x2 = (-b-sqrt(d))/(2*a);
            if(x1>=x2)
            {
                swap(&x1,&x2);
            }

            printf("root1 = %.2lf and root2 = %lf;\n function = %lf",x1 , x2,f3(x1,x2));
        }

        else if (d == 0)
        {
            double x = -b/(2*a);
            printf("root1 = root2 = %lf;\nfunction = %lf",x,f2(x));
        }

        // if roots are not real
        else
        {
            printf("there are no real roots;\nfunction = %lf",f1(a,b,c));
        }

        return 0;
    }