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