Suggested Solution 
(1)
#include <stdio.h>
#include <math.h>		/* to link mathematical functions */
main()
{
flaot a, b, c, X1, X2;
printf("Please enter coefficients a, b, and c for  the polynomial:\n");
scanf("%f%f%f", &a, &b, &c);
if (a !=0)
	if (b*b >= 4*a*c)	
		{
		X1 = (-b + sqrt(b*b - 4*a*c))/(2*a);/* First root */
		X2 = (-b - sqrt(b*b - 4*a*c))/(2*a);/* Second root */
		printf("When a = %4.2f, b = %4.2f, and c = %4.2f:\
  		x = %4.2f or %4.2f\n\n", a, b, c, X1, X2);
	else 
   		printf("No real solution,the square root has no real \ value.\n") 
else
	printf("Not an quadratic equation, the first coefficient entered is zero.\n");
*********************************************************************
(2)
#include <stdio.h> 
main()
{
int in1, in2, inS, inL;
float ft1, ft2, ftS, ftL;
printf("Please enter two integers and two real numbers:\n");
scanf("%d%d%f%f", &in1, &in2, &ft1, &ft2);	/* enter data */
if (in1 >= in2)		/* assign larger integer to inL */
	{inL = in1;		/* and smaller one to inS */
	 inS = in2;
	}
else
	{inL = in2;
	 inS = in1;
	}
if (ft1 >= ft2)			/* assign larger real to ftL */
	{ftL = ft1;		/* and smaller real to ftS */
	 ftS = ft2;
	}
else
	{ftL = ft2;
	 ftS = ft1;
	}

if (inS >= ftL)	/*even the smaller int >= the large float */
	printf("Both integers are larger than or at least equal\
	to both floats.\n");
else
	{if (inL >= ftL && inS >= ftS)	/* but inS < ftL */
	 	printf("The large integer is larger than the large float, and the small integer is larger than the small float.\n");
	 else


		{if (inL >= ftS)
		 	printf("At least one integer is larger than one float.\n");
		 else
			printf("Both integers are smaller than the floats.\n");
		}
	}
}
*********************************************************************
(3)
#include <stdio.h>
main()
{
int n, i, even_sum, odd_sum, start, end;
printf("Please enter an integer:\n");
scanf("%d", &n);
if (n >= 0)		/* for non-negative n */
	{start = n;
	 end = 2*n;
	}
else
	{start = 2*n;		/* for negative n */
	 end = n;
	}
for (i=start; i<=end; i++)
	{
	if ( (i%2) == 0 )		/* for even values */
	 	even_sum += i;
	}
i = start;
while ( i <= end )
	{
	if ( (i%2) != 0 )		/* for odd values */
		odd_sum += i;
	i++;
	}
printf("The sum for all even numbers between %d and %d is %d\n",\
	start, end, even_sum);
printf("The sum for all odd numbers between %d and %d is %d\n",\
	start, end, odd_sum);
}