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);
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~