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

Question

7.4k views

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

[Exercise] Coding (C) - asked Oct 26, 2017 in Chapter 5: Selection Statements by semicolon (5.2k points)
ID: 28934 - Available when: 2017-10-26 18:00 - Due to: Unlimited
reopened Oct 26, 2017 by thopd | 7.4k views

56 Answers

Page:

1
2
3
4
...
6
next »

The Judge · Answer 1 · 2018-01-18 18:03:30

Hidden content!
#include <stdio.h>
* *  * ** *** **
int main()
{
***   * ********* ***** * ** *  * * **  ***  *  **** **   **
    *   ****** * * * ***  * ****** * %f   ** *** * **  * * * ** *    ** ** **
* * * *  **   *  * ** ****  = (b*b-4*a*c);
          **** *** *   ** **  = (-b + sqrt(D))/(2*a);
 **  *** **** * ***  *    *   **  = (-b - sqrt(D))/(2*a);
  *  *  ** * ** **  *  **  * *  = -b/(2*a);
 *  *****   *    **  *  ***      * *   =sqrt(-D)/(2*a);
** ****  *     * * ** **** * * *** *  
 ******* *   ***   **    ** 
* ** * *****  **  *** **       * * **  *  **  *        *    **   of %.2fx^2 + %.2fx + %.2f = 0 are real and ** **   * * * * *** *
  *   *****   *  **   * *  ****    ** ** * ***   * **  **** * *  = %.2f\nx2 = %.2f",x1,x2);
**    * * *** *   ***    * 

 *** ********    *** *  *     ** if(D==0)
 * *  ** * *       * *  * *** * 
*  ***   ****  ***  * * ***    **  * ***   * *  *  **  **   ****  **  of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",a,b,c);
**     ** * **  **     **   *** *   ** **  *   *   * **   **  ** = x2 = %.2f",x1);
*****  *  **** *    ** *  ** **  
 ** ***   * * *** *   **   * * 
    ** ** **  *  *   **   * *
*  *    * **    ** **  ** ***   *   ***  **** * ***      * * ****  of %.2fx^2 + %.2fx + %.2f = 0 are complex and   *** ******** 
*     ** * *     ****  ***     **  * *    *  *** ** ****   *       =  ***  *  *   * *** * *  *  ***    
* ** ***  *   * * *    **  ***     * ***  * *        * * *    = * *    *     *** ***  * * **  * 
  ** ** * * *** *   *** ** *  *
***  *  ** *    *  ****  *****  *  * 0;
}

answered Jan 18, 2018

Mukhammed · Answer 2 · 2018-01-12 20:12:13

Hidden content!
** * * *****        
 *  *** * * *       *

int main()
{
**    ** ********* *********   ** ** ******* * *
 *     *   ** *****  *  * **** * **  *****  **   *  * *   *** ** **   * *********
**  *  *      ***  ** ****  =  * **  *  * 
 ***   *  ** ***  *  ****** ***  * * * *  * *
 * * *****   * *  * *     
** ** *  **     *     ***          *** *
* **  * ***  ***   ** *   * *****  = -b /(2*a);
*********   **   *   * **  *** *** ** *  * **  
    *   ** **   *****    * **     = (-b)/(2*a);
* **  * *  *  ***  * *   ** *  * **** of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f+%.2fi\nx2 =  ***      * *  * *    * ***
 **** *      * ** ** *    **
 *** * **    *  * *** **    if(D==0)
***  * * *     **         
  ****  *** *  ** **    = (-b +  *******  * 
*  *  ** * ****     * *   ***  * = (-b - * **   *
* * * **** *   ***    **** ***  ** **  of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 =   * **   * * *** 
* *  **    *     ***   
   *     * * **  ** * *  if(D>0)
*  ** * *   *   ***** *     
* **   *****   * ****  *   * *  = -b/(2*a);
 *****         *  *  ** * **  = (-b +   **** *
 *** *    *   *   *  *   ** ** = (-b -    * **  *
  * *  * * ***  **   * *   **  *****  **    of %.2fx^2 + %.2fx + %.2f = 0 are real and different\nx1 = %.2f\nx2 = ****** *  * *
**  ** **  **  **      *** ***  
 ***  * **      **   **     0;
}

answered Jan 12, 2018 by Mukhammed (-323 points)
edited Jan 12, 2018 by Mukhammed

watty1998871108 · Answer 3 · 2017-12-08 04:28:05

Hidden content!
#include  *     *  ****  
#include   *** * **  * 
int main()
{
 * ***  ****** * **** ******   * * *  a,b,c;
  *  *****   *     *****  *** * **  * *** *      *   ** ** ***  ***** * 
*  ***  * *** * *  * *  
  * **   * * ** *   **   * **** * *  * ****
   *  * * *  * * *     *
* * ***  **  * **      * **** ** ***  *    ******* * ***** **** *  of %.2fx^2 + %.2fx + %.2f = 0 are real and different\nx1 = %.2f\nx2 =  ** *  ** *      +  * ** *   **  *****  -  *   *   *    ** **
* *    **      * *** **   
*  ***** **  ****    *    **** 
**  *** ****  **  * ** * * ** *** if (b*b-4*a*c==0)
****  * ****    *  *  **    *
*    *  ** ****       *     * *   *    * **   * **   *      **** ***  of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = *  * **** ** **  +     **   **** ***
* **   *    * ****  **  ** 
     * *     ** *  **  ** * 
*      *  ** *  *  *  * *  *    * 
* ** * *  *   ****  ***** *** *
* ** *** *      ** *   ******         *** *  ** **   ** * **   * * of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f+%.2fi\nx2 = * *   ** *    ** *     ** *     ***** *   ***   * *** **  **** 
** *   **    *  ** **   **  
   ***   *  ** ** *    *   **    0;
}

answered Dec 8, 2017 by watty1998871108 (-127 points)

watty1998871108 · Answer 4 · 2017-12-08 04:24:41

Hidden content!
#include     ** *** ** * * 
#include     *   **  * 
int main()
{
*  ******* *  *  ***      * * a,b,c;
   *** *  *   * ***    *** **   **    *      * ***** * **** **   ****  ** * *
* *  * ** *** *** *  ** **** * *
*    *  ** *       **   ***** *** ****  **
  ** ***    ** *  *  ** **** 
 *    *   **   * * ***  ****  ****  ********* **** ** *   ** *** *  *   *  of %.2fx^2 + %.2fx + %.2f = 0 are real and different\nx1 = %.2f\nx2 = * *  ** ** * * * + *  *** * ** ****  -  ** **  *** * *     
**    ** ** ***  ***  *   
   *   * *  *        *  *  
**  *   ****   * ***   *** ** *** if (b*b-4*a*c==0)
*     *  ** **   *  ***     
   * *** ** * *  **** *** ***   * ** ** * **  *** *   *     **** **  *   of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 =   * * * **      * +  * ***  *  ***  * 
*****   * ** *  *** ********
* *******    * *   ** * *  * 
  *      **  *   ** * * * ***** **
 *    *   **** * *******  ***   
         * **    * * * **** *   **** *  * * *   ***       * *   * of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f+%.2fi\nx2=    * ***** ** * **   *  **  * * *        *  *  *  ** * **  ** * **  ***
 *  **  *     *  * **** * ** *
*  **    *** * * ***  *  *** *** * 0;
}

answered Dec 8, 2017 by watty1998871108 (-127 points)

fung2004067 · Answer 5 · 2017-11-15 13:51:14

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

answered Nov 15, 2017 by fung2004067 (-214 points)

林上智 · Answer 6 · 2017-11-15 11:19:17

prog.c:2:12: error: expected declaration specifiers or '...' before string constant
     printf("\xe8\xab\x8b\xe8\xbc\xb8\xe5\x85\xa5\xe4\xb8\x80\xe5\x85\x83\xe4\xba\x8c\xe6\xac\xa1\xe6\x96\xb9\xe7\xa8\x8b\xe5\xbc\x8f\xe7\x9a\x84\xe4\xb8\x89\xe5\x80\x8b\xe4\xbf\x82\xe6\x95\xb8\xef\xbc\x8c\xe5\xa6\x82 aX^2 + bX + c = 0\n\xe4\xbb\xa5a b c\xe8\xa1\xa8\xe7\xa4\xba\n");
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.c:3:5: error: expected identifier or '(' before 'while'
     while(scanf("%d %d %d", &a, &b ,&c)==3){
     ^~~~~
prog.c:29:12: error: expected declaration specifiers or '...' before string constant
     printf("\xe8\xab\x8b\xe8\xbc\xb8\xe5\x85\xa5\xe6\xad\xa3\xe7\xa2\xba\xe7\x9a\x84\xe4\xb8\x89\xe9\xa0\x85\xe4\xbf\x82\xe6\x95\xb8");
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.c:30:12: error: expected declaration specifiers or '...' before string constant
     system("PAUSE");
            ^~~~~~~
prog.c:31:5: error: expected identifier or '(' before 'return'
     return 0;
     ^~~~~~
prog.c:32:1: error: expected identifier or '(' before '}' token
}
^

410330002 · Answer 7 · 2017-11-14 20:50:25

Hidden content!
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

int main ()
{
 *  *  * ** *** **  ****    a,b,c,D;
 ***     ** **  ** * ***** **   ***  x1,x2;
*******  ****  ***** *  * ** ***** *** ** %d * ** *  *      * ** * *  *

* ** **  ***  * * *   *  *  * 
   ** *** *  **** * *     *   * *    ****
 *  **** * ** ***** * *** *  *  **  * *

**  ******  ***  *   *  * **      A,B,C;
   *  ** * **    **** *  ** * * ** * *

***   *  *  **  **   ** **  ** * *   *  
****** *    ***    *** * *    *  * ******   ** *** *     ** ** *** of %.2fx^2 + %.2fx + %.2f = 0  are real and   *******   *** **
 *   *  *  ** **  * * ***** * ****** *** * * *  **  **** * **  *  ** ****  *  = %.2f\n",x1);
 * *  ******    * * *  **** *** *  **        **   ****** *    *  ****  * * = %.2f",x2);}

 **     **** *    **  **       if(D==0)
*** *  * * **  * * *** *  ** * ***    **  * * *   * * **  *** ***** **  of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",A,B,C);
 **  * ** *** **  * ** * *  * *  ** * *   *   *   ***** *    ** = x2 = %.2f",x1);}

* *** ** * *   *   * *    * * if(D<0)
**      * * * *** *    ** * ****    ** ***  *** *   *  ** ** **    * * of %.2fx^2 + %.2fx + %.2f = 0  are complex and    **  *  ****      
*   **** *  *      *  ** *   * ***   *  *** ** **  * **  *  *  bb,d,dd;
*   **  **  * ** * ** ** ***** * *  *  **** ** ***     ******      *  * 
   **  * ***   * * ******   *    **** * *  * *******  *  * * *** ** * *  ** ***
  ***** * *   ** ** *** **      *     ** *   *  *  **** **    ****** * = * *    **   **   * *
 *        * *** ** **   * **  ***     *** **  ** * **  * **  ** * **   = * ****** *** ***  * *** 

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

answered Nov 14, 2017 by 410330002 (-16 points)

The Judge · Answer 8 · 2017-11-14 15:45:56

Hidden content!
#include <stdio.h>
 **   *  *    *** **    
int main()
{
**  **   *** ** ******* ****    *  **** ** *   *  
*****  * *  *  * *** ********    * **  %f  * ****    ****** * *** * **  * **
*** * * * **   *** ** ***  = (b*b-4*a*c);
 ****   ******** * * *    = (-b + sqrt(D))/(2*a);
 * * *** *    *  *  *** ***  = (-b - sqrt(D))/(2*a);
****  *    ** ***  * **      *  = -b/(2*a);
 *** **  * ** * * **     *  *   =sqrt(-D)/(2*a);
***  * ** *  ** *  *  * **      ** 
*  * *        * ** * ***** 
 *    * ***** *****          * *        ** * *** ***  *** * * ** ****** of %.2fx^2 + %.2fx + %.2f = 0 are real and  *   ***      ***  
*  ***  ***     ***       ******** ****      * **  ***       *   **   = %.2f\nx2 = %.2f",x1,x2);
****    *  **    ***    

*  * *    *  ***  ****  **  **** if(D==0)
  *** **   **** *   *   * * * *
 ***    *  **  **   *  * **   *** **  * * **  **    *** *** **  **  of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",a,b,c);
  *  * *    ** *     ** **** **** *  **  * * ***    **  ** *  = x2 = %.2f",x1);
 * *    *** *****    * *   *** 
  * *  ** * * * * * ** * * *  
   *** ** ** *      *  ******** 
**  **  **   ** *      *   ** *   *** **   *  *** *  *  ***** **  **   of %.2fx^2 + %.2fx + %.2f = 0 are complex and  **  * *    *  *  *
 *  ****   *** * * * **** *  ***** **** **       ******  ****  ***  = ***       * *  *  * ***  *** 
** ** ** **** *  ** ** ** *** * ** * ** *   *   * *      * *  * * * = *****  * ** **    *   *
 *    **** ** ***      *
*     ** **   * ** **    * ** ** 0;
}

answered Nov 14, 2017

The Judge · Answer 9 · 2017-11-14 15:44:34

Hidden content!
#include <stdio.h>
    ***  ****** ** *  
int main()
{
** **   * **** * *        **  *  *  * *        **  *   
  **** * *  ****   * * **  * *  * **   ** *   %f  *  **  ** *  *** ****  *  *  
*  **    **  *  **   * **   *  = (b*b-4*a*c);
* ** *   **** * **  *      * = (-b + sqrt(D))/(2*a);
  ***** ** ****  **** * ** * = (-b - sqrt(D))/(2*a);
 *   *   *  * ** * ****   *    * **  = -b/(2*a);
 *    *** * ****** ** **      ** =sqrt(-D)/(2*a);
  *** *** **** ** **  **   *     **
* * *  **** * * * ***  *  
****   *** ***  **  **  *     *  * * ** ***     *    *  ***   *** ***    * of %.2fx^2 + %.2fx + %.2f = 0 are real and    * * **  ** ** *    *
**** *   **  *   * *** *  *  * ********* ****    *  * * ***** = %.2f\nx2 = %.2f",x1,x2);
   ** ******     * *   ** * *

** **** **  ***    * *** * * if(D==0)
**  *    *** *** *    * * **
*  **    * *   ** **     * **** *  *  * ** ****** **   ***** ** *    of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",a,b,c);
 *   *  * **    *****  * * *   * * ****  *******  ***** * * *** = x2 = %.2f",x1);
* *   **  * *  **  *  *  *  ****
* *     ****** *  **   *   
  * *   ** *  * *   ******* *
* *  ***** *  * *      * *** **  ***    *   ***    ***       *  *    **  *  of %.2fx^2 + %.2fx + %.2f = 0 are complex and ** **  ***  ***   **
*    ** * *  * ** *****  ***  *** ** ** ***** *  *****  *    * = **   ** * *   ** **** ** * *******
*** *** **  * *     * *       * * * ** * *  ** ** * * **** * *  *  ***  =    * * ** * *  *  * *  *  * 
*  *   *       * **    
** * *    ** ** *  ***** *******   0;
}

answered Nov 14, 2017

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

Please log in or register to add a comment.

56 Answers

Please log in or register to add a comment.

Please log in or register to add a comment.

Please log in or register to add a comment.

Please log in or register to add a comment.

Please log in or register to add a comment.

Please log in or register to add a comment.

Please log in or register to add a comment.

Please log in or register to add a comment.

Please log in or register to add a comment.

Please log in or register to add a comment.

No related questions found