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