Problem
Applying the software development method to solve any problem in C Language
Solution
- Find roots of a quadratic equation, ax2+bx+c.
- There will be 2 roots for given quadratic equation.
Analysis
Input − a,b,c values
Output − r1, r2 values
Procedure
$r_{1}=\frac{-b+\sqrt{b^2-4ac}}{2a}$
$r_{2}=\frac{-b-\sqrt{b^2-4ac}}{2a}$
Design (Algorithm)
- Start
- Read a, b, c values
- Compute d = b2 4ac
- if d > 0 then
- r1 = b+ sqrt (d)/(2*a)
- r2 = b sqrt(d)/(2*a)
- Otherwise if d = 0 then
- compute r1 = -b/2a, r2=-b/2a
- print r1,r2 values
- Otherwise if d < 0 then print roots are imaginary
- Stop
Implementation Code
# include<stdio.h>
# include<conio.h>
# include<math.h>
main (){
float a,b,c,r1,r2,d;
printf (“enter the values of a b c”);
scanf (“ %f %f %f”, &a, &b, &c);
d= b*b – 4*a*c;
if (d>0){
r1 = -b+sqrt (d) / (2*a);
r2 = -b-sqrt (d) / (2*a);
printf (“The real roots = %f %f”, r1, r2);
}
else if (d= =0){
r1 = -b/(2*a);
r2 = -b/(2*a);
printf (“roots are equal =%f %f”, r1, r2);
}
else
printf(“Roots are imaginary”);
getch ();
}Testing
Case 1: enter the values of a b c: 1 4 3 r1 = -1 r2 = -3 Case 2: enter the values of a b c: 1 2 1 r1 = -1 r2 = -1 Case 3: enter the values of a b c: 1 1 4 Roots are imaginary