10-26 Exercise 3: Find roots of a quadratic equation

Question

Write a program to find roots of a quadratic equation

A quadratic equation is a second order equation having a single variable. Any quadratic equation can be represented as where a, b and c are constants ( a can't be 0) and x is unknown variable. 

寫一個找二次方程的求根程式

For Example

 is a quadratic equation where a, b and c are 2, 5 and 3 respectively.

To calculate the roots of quadratic equation we can use below formula. There are two solutions of a quadratic equation.

使用下列公式:

x = (-b + sqrt(D))/(2*a)
x = (-b - sqrt(D))/(2*a)

where, D = (b*b-4*a*c) is Discriminant (判別式), which differentiate the nature of the roots of quadratic equation.

For the complex result (複數根):

realPart = -b/(2*a);
imaginaryPart =sqrt(-D)/(2*a);

Note: We have used sqrt() function to find square root which is in math.h library.

 

Example input 1:

1 2 1

Example output 1:

Roots of 1.00x^2 + 2.00x + 1.00 = 0 are real and same
x1 = x2 = -1.00

 

Example input 2:

1 -3 2

Example output 2:

Roots of 1.00x^2 + -3.00x + 2.00 = 0 are real and different
x1 = 2.00
x2 = 1.00

 

Example input 3:

1 2 2

Example output 3:

Roots of 1.00x^2 + 2.00x + 2.00 = 0 are complex and different
x1 = -1.00+1.00i
x2 = -1.00-1.00i

Comments

We will continue this question in few days

---

Everything is fixed. Enjoy your time with The Judge :)

---

ANNNNNNNNNNNNNNNNNNNNNNNNNNGRYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

---

Your code has newline at the end sometime. You learned this lesson many times!

---

After i correct the newline in my code,there is still wrong output.However,I had run the program in Codeblocks.The output is still as well as the result. Seeking for help.

---

your output lack of 1 space at line 8 when print out "Roots of ...". Please be careful with all small details when working with online judge

Answer 1

Hidden content!
#include ** *** ***      *
#include  **   ** ***

int main()
{
* **   * *  * * *    ***     *** a, b, c, determinant, x1,x2, realPart,  * **** 


 ** **** *** ** ** *** *   ** *  **      %lf * *   **   *  **   &b, &c);


* ***   ** ***   *****    ***** = b*b-4*a*c;

  **  ** *** **** * ****  condition for real and different roots


* * ** *****  ***  **  * **   * ****** for real and equal roots
  ***  *   ****  *       *** * (determinant == 0)
 ** **  *  ** ** *  *    * 
 *** ** *  ** **  ***    ** * ** **** * **      * **      = x2 = -b/(2*a);
***   * *** *    *  ** **  ***** ***  * * *    *** ** ** **  * ** *  of %.2fx^2 + %.2fx + %.2f = 0 are real and  *   *  **    a,b,c);
 *  *   *   ** * **  ******  * * ** **** * *   ***   *    = x2 =      **  * ** x1);
* ** *  ****   * * ** 

 ** ** ****  * **** * **** **   * * *   if *** ** * > 0)
 *    * * * *     ** * *  *** 
*    ***    **  *    ** *** * ** sqrt() function returns square root
***  *   * ** * * **  *  * ***  **   * *   *    ** * * = *** * * ***  **     
 **   * *  *  * * ** * *  ***** * * * ***   **   **   **   =   ***  ***  * **  *

** * **   *  *** *  *** *      ***   ***  ** *   ** ****** *    of %.2fx^2 + %.2fx + %.2f = 0 are real and * *        * *  
 ** **  **  * * * *   * ******    *    *   *   *    **  ** **  *  * *   = * * *  ** x1);
   *    *  ***    *  ** * *** *  *     **   **** * * **     *  *   =  ***  **  * *  x2);
  ******  *** * * *  ***  if roots are not real
*  ** * **   *   *  ****  ** 
   *******    *  *****  
   *******   ** *  *  * * ***  ***** **      *****  *** *   ***  = -b/(2*a);
* ** **  *  **  * ** *** * ** *****  *  * ****** *  *  * **   **  ** = *   ** * **** ***
  *    *** * *  *   *  * **   ** **   *  *** ** ***** *  * *      * of %.2fx^2 + %.2fx + %.2f = 0 are complex and   * ****  ** *** * a,b,c);
** * ** *  **** *      * *** * **   *  *   * ** *** * **  *****  =    ****  *** * realPart, ***     *** ***
 *   *** **  *  * *  ***  **** ** * *  ** *   *     **  ****  *  **  **  =   * **    *  **  realPart, ** *  **
**     *****  ***   **  * * 

   ****** ******* ** * *** * 0;
}

Comments

Case 0: Correct output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 2

Hidden content!
#include *****    * ***   *
#include  ***** **** 

int main()
{
 ** ** *  **  * *  *** ***     a, b, c, determinant, x1,x2, realPart,  *    * *   *


  * * * *   *  **    *** ***** ***** %lf * ** ***   *    &b, &c);


** *  * *  *  *   *     ******   *** * = b*b-4*a*c;

  *  *** **    *  ** **    *  condition for real and different roots
* * * **  *** * * ** ****  * (determinant > 0)
 * ** * *  ** *** ******* 
   ***  ******   *  ****  sqrt() function returns square root
***  ***   ** *****    **   **  *  * * *  * ***** ** =    * ******   **  
  **** **      ***  * ****  ** *   * ** ** **  * ** = **   * **  * *** *  ***

***  * ***  * *   ***          * **   *    *** *** *  *     * *  of %.2fx^2 + %.2fx + %.2f = 0 are real and *  * ** * * ** * *
  *     ** **  * **  * *** ** *  * * * * *          ***   ** * ***  ****  *   = * *  **  *** x1);
***  *** *****   **   ***    * * *           * ***   ****** **    =  * * *   *     x2);
*** *     *** *    *    * **   *

*****   ********  * ***        **    **  for real and equal roots
*  * ***  *    * *** * *  * if (determinant == 0)
*** **   ** *   *** *  **
** * ****   ***** *  **   * *  ** *  * *          **   * * **   = x2 = -b/(2*a);
*****   **  ** ** ***    * ***    * **  * * *  * *  * *** *  *    ***  *  **** of %.2fx^2 + %.2fx + %.2f = 0 are real and  ** ** *** * a,b,c);
     *    * *    *     ***  *      * * * * **  ** *** * *  ** = x2 = *  * *   x1);
  * ****  *    ** **     ** *

   **  ****** * *    ***  ** if roots are not real
 ******* *    ***   *   * * **
*    *****  ***  ** **** * *
*     **  **** * * *  ***** * *   **    **   **** ***  *** ** = -b/(2*a);
*  **    * * * *  *   * *  **   * *  ***    * **** *  *  *   =  **    * * * ** *
  *  * * ** **  ** * * * **   *  * *  * ***** * ** * **    **  **    ** of %.2fx^2 + %.2fx + %.2f = 0 are complex and   * *   **    a,b,c);
***  *** *  ** ** **   *    *   *      **  ***    ****** **  *** = ** *** * *  *** realPart, *   *  
**** * *   *** *  **** * **   *     *   *  *      * * **     *** *   * *  =   *** * ***       realPart, * *   ***  
*** *    *     * ** *** * **

 *   ** *      *       * *** 0;
}

Comments

Case 0: Correct output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 3

Hidden content!
*****  * * *   *  *    
 *  ** **  ***    ****
int main(void)
{
*   **   * ****          * a,b,c,d;
* **   * ******  ***      *  * ** **  **  %f **  *    ** ** *  **  *  *   *
   ***   *  * *    *  *** *** 
** * * *****  ** * **  ** *   * *** **
****  *    ** ***  ** *** *    *      *** *  ******  **  * *    ** *  ***** of %.2fx^2 + %.2fx + %.2f = 0 are real and  ** *    = %.2f\nx2 = *** *    *  * ** +  **   **  *** -  *   **** 
* * ** *** * ** *  ** ****  * *
  ** ***** ** **** *  (d==0){
     * **  *   *  *    * * * ** **  * * **  *     ****    *  **  * of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = **** **   *****  +   *** * ***  
*     * ***** ***   * *  * 
 **   **   *   *   ** *  *   ** (d<0) {
 ** *   *** *** *** *  * **  ****** ***    *** * *   * **  * **  * of %.2fx^2 + %.2fx + %.2f = 0 are complex and ** * *   = * * * ** =     * ********* *  ** *** ** *** *   **      **   *  ****  
***  *** ***  * **  * * 
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 4

Hidden content!
 *   *   *  ** ** *   
* ** *** *** * * *** 
int main(void)
{
* *    **     * ******* **  * a,b,c,d;
   *   * ***  *   *** **  *** **  **** %f  ** *** ** * * **    *   *     *
*     ***** **** ** * *****   
  *** ****** ****    ****   *  (d>0){
** ** ***  * * * *** **** **  **    **  **  *  * ** * * *** ***  ******   **  of %.2fx^2 + %.2fx + %.2f = 0 are real and  **  **** = %.2f\nx2 =  *** **** ** **  +  * *  ***   - *    *      
** ** **      * **** ******* **
   ***  **   * ** * * *  * (d==0){
* *   *  * *   *  *  ***     * * * * **  ***** *    ** ***** *****  *  * of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 =  *** ***  **  **   + * *  *    *
***** *       *** *  ** * ***
    *  * **     **   * *   {
 *** ***    **    *  * ** *  * **  *         * *  **  *   *   * * of %.2fx^2 + %.2fx + %.2f = 0 are complex and * ****  ** =     *   =    **    **   **  **   * ******* **   **   *   ** 
** *  ** *  *   * * *  **
}

Comments

Case 0: Correct output
Case 1: Wrong output
Case 2: Correct output
Case 3: Wrong output

Answer 5

Hidden content!
#include<math.h>
int main()
{
*     *** **      ** *  *** *  a,b,c,d,x1,x2,x3,x4;
 **      *  ***** * *  *****  **   *  * *  %f   ******   ***   *   * *  
* *  *  * * ***** *** **** *  *  *
** *** *  * *  *   ** *  **  ** * * *****
**  ** **  * **** *** *  *   * * * ** *   ***
* ****  * *     *   ** *   *  **  * *
**   *   ****    * ** *   ***   **** ** 
 ** *   **  *     *    **** *    *   *  **   ***   **
  * *   **      * ***  * * **
 *** **   * *****  ** **    *  ******** *  *** ** **  *  **  *  *  of %.2fx^2 + %.2fx + %.2f = 0 are real and * *     ** ** ** * *  *  *  ** *  
 ****     ****   * * * ****
**  **    * ** *   * ***  *     **  **** *** * * * ******  *   
 *   ***** ***** *  **   *  
     ** * * *   * ** ****  * * **   * *  ***   *     ****** **  ** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
*** * *    **** * * * ***** 
*  *** *    ** ****   ** *  *    *     *  **    * *   ***   *  
*  ****     * *      * ** 
  * **  *** ***** **  * * * **  * *** * ** **** * ** **** *   ***   of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f+%.2fi\nx2 =  ** * ***  ** ** **   **  
  **     *** *    * *  **  *****
** **   ****    ** ****   *    * 0;
}

Comments

prog.c: In function 'main':
prog.c:5:5: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
     scanf("%f %f %f",&a,&b,&c);
     ^~~~~
prog.c:5:5: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:5:5: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:13:9: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are real and different\nx1=%.2f\nx2=%.2f\n",a,b,c,x1,x2);
         ^~~~~~
prog.c:13:9: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:13:9: note: include '<stdio.h>' or provide a declaration of 'printf'
prog.c:17:9: warning: incompatible implicit declaration of built-in function 'printf'
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
         ^~~~~~
prog.c:17:9: note: include '<stdio.h>' or provide a declaration of 'printf'
prog.c:21:9: warning: incompatible implicit declaration of built-in function 'printf'
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f+%.2fi\nx2 = %.2f-%.2fi",a,b,c,x3,x4,x3,x4);
         ^~~~~~
prog.c:21:9: note: include '<stdio.h>' or provide a declaration of 'printf'

Answer 6

Hidden content!
#include<stdio.h>
#include<math.h>
int main()
{
    *     *     **   **  *** ** a,b,c,d,x1,x2,x3,x4;
  ***    *** *** **  *  *    *  ** %f  *  ** ** ********* ****   **    
** *    *    * ** *  **** * *   *  **
*  ***  ***      ****  ***  ***  * * **** *
  *  ** **** *  * **     *****    **  ** * 
**   *  *  *    ** ** *** **  ** * **
*   **  ***  ***** ** **    ** ***   
  * **  * **   *    ** *     *  ** **    * *    **
*      ** *   ** *    *  
  *  **  *   *****     *    *  *    **  *  ****** *     * *** ** *   *       *    of %.2fx^2 + %.2fx + %.2f = 0 are real and *****  *  **   *      ***  *   * * *   
** *** *  *  **  *****   * *
       * *   ***   ** * *  *     * * **   **   ***   ** ***
*****  *  ** *   ******   
******* **  ****    *   **    *** * * **   * ** *    ** ***** ** * ** * of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
* ***   ****    **  ***    
****** **  * *  * ** * *  ** * * ***  *  *** **   
***  ****   * ** *** *** ** * 
**  ***  *  ****   **  ** * *  **    *   *   **  **** *********    *  *   of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f + %.2fi\nx2 = %.2f -  ***   * * **      *** *  **
** *     * ******    ** *   *  
 **   **** *  **     * * *   * *  0;
}

Comments

Case 0: Correct output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 7

Hidden content!
#include<stdio.h>
    * * *   * *  *
int main()
{
*** * *    **     ***  * *  * *    * a,b,c,d,x1,x2,x3,x4;
***  *  *** * **   *  * **            **** %f ****   * * **   ****    ****
  * *    * * *****    ***
* *    ** * *    **** * *  *    *
**  * * * * **  **    * ** * **    *  *** 
  *  **    ***  ***     * * **   *  ***
  * ******  * **     ******* **  * *  *
**    * * ***** *    *  *** ** ** ** *  *  * *  * ****
*  ***** *  ** ** * **** ** 
 * **  **      *    **    **  *** *  **  ** * * ** *** **  ***      of %.2f x^2 + %.2f x + %.2f = 0 are real and *****  *  *  *  ** *  **** ** *   *  
*  *****    *  ** ****** 
   *    *  * ** **     * ** ** ** *   *  **  *   * ** *** **
 **  **   *   * *  * *  *   * **
**   *      * * *   *** *  **  ******  *****    * *** *  * **   * * * of %.2f x^2 + %.2f x + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
* *** * ** **** **** *  *  * ***
 **  * *   *    * *  ** *  **  ** **  *    ** *   ********  
*  * * **     ** *** * * ** * 
 *  **    * **   * * *  *    *  * *   ** **  * *** *  **     *********  of %.2f x^2 + %.2f x + %.2f = 0 are complex and different\nx1 = %.2f + %.2fi\nx2 = %.2f -      ** **  ****   *
*  ***   **  ** * ***   *
   * *** **  ** *  ***** *  * ** 0;
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 8

Hidden content!
#include<stdio.h>
#include<math.h>
int main()
{
 **  *  *   * *   *  *  ***  a,b,c,d,x1,x2,x3,x4;
**** *  **    *    ** *** *   ***** *  *   %f ** *  * * * * ** *  **    ** ** ** 
 *** * *** ** ** ** ***  * *  * * ****
* * ** ***  * *** * **  *******  
**     *  * ** *    * **      * ***   **
        * *****   ** *  * *    * **     
 **  *    * *   * *  * ****** *** *  **** 
****  ****  *     **** ****** ***  * ***  *  *   **  
* ***  *  * * * * ***  * **   **
* ** *** **  **  * **** *  *** *  ***  *   **   ****  **   *   *  * * of %.2f x^2 + %.2f x + %.2f = 0 are real and  * * **   **     **     ** * * * ** * *
 ***  *  * *  **     *   ****   
    ***  *  *     ** * * *  *    ** ********  *
 ***  **** ***  * *** ***  
 *      ** ** * *****  *** * **  ** * ** ****** *  *  **  ******  of %.2f x^2 + %.2f x + %.2f = 0 are real and same\nx1 = x2 = %.2f",a,b,c,x1);
 *** *           **   **
 * *  ** * ** *  ** ********  **** * * * ** ***  **  ** *
** * ****    ***** ***  * * 
*      *** * * **   * *  **** * ** *****  ** **    ** *  *   ** ** *  * of %.2f x^2 + %.2f x + %.2f = 0 are complex and different\nx1 = %.2f + %.2fi\nx2 = %.2f -  *   **  * ** * *** 
 *******  ***  *    *   *  * 
**   ** * * **  *      *  * *** * ****    * ****
**  *    * ***  *** * *   * *** **** 0;
}

Comments

prog.c: In function 'main':
prog.c:24:5: warning: implicit declaration of function 'system' [-Wimplicit-function-declaration]
     system("pause");
     ^~~~~~

Answer 9

Hidden content!
#include<stdio.h>
#include<math.h>
int main()
{
  * ** * ** * * ** ***      *  a,b,c,d,x1,x2,x3,x4;
   ***** *      *** *  **    *** *  ** %f *   ** **   *** * **  * *  * 
  *   **** **  **    * *      *  * ***** 
 ** ** ***** * ****   *      **  * ****   
 *    **    * ** ****   *    ** *  **    *** *
***** ** **    ** ** *  ******** ** * 
  **   * * **   ** * *** * **   * 
**** **    ** *****  *  *     * *   *  **    * ** * *  
  ** *  *    *** *** ******** *  *
  **  * ****  ** ** ** ** *  * ****** ** ****  ** ****  ** *    *** of %.2f x^2+%.2f x+%.2f=0 are real and different\n x1=%.2f\n  * *  *    *  * ** **  
******* *     *       * **
* ** ***   *    * ****** *   **    ***    * **  ***   ** *
*   *   * * *   ***    ****   
***     *    * * * ** *****   * ***** *       **  *       ****    ***   ***  of %.2f x^2+%.2f x+%.2f=0 are real and same\n * * ***** **   ******* *
  * ******* *  * **       *  
 *** * **    *  **  * ***      * ** *       ***** * **  
**     ** ** **   ** ***  **
 *******   **  * **  ** * * *   ** *  ** * **       *    *   **  of %.2f x^2+%.2f x+%.2f=0 are complex and different\n x1=%.2f+%.2f i\n x2=%.2f-%.2f ** * ******* ** *
 **  * *   * ** * **  * * 
    * ***         **   ** ***  0;
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 10

Hidden content!
#include<stdio.h>
#include<math.h>
int main()
{
*   ***  * *** **   *  * * **  * a,b,c,d,x1,x2,x3,x4;
 ** *** **        * *  * *     *** *  * *  %f *******  *   *  *   *** **
   ***   ** * *  ** **  **  * *  * 
**      ***** *     ***** ***  **        
 * *      *    **  *** * * *     *  * ** *   
******   *  * ** * * ** *    **   * * * 
* **    *  **  * * *** *    *    * *  * * * 
*  *    **     **     *    ****  *    *** *  ** **  ** **
**  * *  * ** ** ** *** ** 
  ** *** ** * * ***** *  ** * *   * *****  ** ***          *  * **      of %.2f x^2+%.2f x+%.2f=0 are real and different\n x1=%.2f\n * *   **  ** ** ** *
  *** **   * **  * * ***  *
 **  *  *  *  ** * *  *   *  **   ****  ******  *  *** **    ** 
******* **  * *  * ** *****  
 ****  *    *** *  ***** ** **** ** * * * *****  *  *******   ****  *   of %.2f x^2+%.2f x+%.2f=0 are real and same\n *  * ** ****    **    ***
   *   **  * *  ****** *  ** *
 **  *  **   * *    ***   ***** ** **   ******* *   * ** *   * *
* ** * *   *  * ******  * **
 * * ** * *   *** *  * **   * ** **  *****      * *   **   *  * *** of %.2f x^2+%.2f x+%.2f=0 are complex and different\n x1=%.2f+%.2f i\n x2=%.2f-%.2f  ** *     *    *   * ****
***  ***  ** *    * *  ** **  *    
*  ** ***  ***  *   * ** ******   0;
}

Comments

prog.c: In function 'main':
prog.c:18:16: warning: too many arguments for format [-Wformat-extra-args]
         printf("Roots of %.2f x^2+%.2f x+%.2f=0 are real and same\n x1=x2=%.2f",a,b,c,x1,x2);
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~