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

Question

2.4k 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 | 2.4k views

56 Answers

Page:

« prev
1
2
3
4
5
6
next »

The Judge · Answer 1 · 2017-11-02 18:13:29

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

int main() {
 *   *  *** **  **  **   * *** ** **  *  * 
 *  * *      **** ***  *  **  * ***  ** %f       *  &a, &b,   ** *****
* * * * **** * * **   ********** *** *
 ****      * *** *       * *  * * ** {
**   ***   *  * ***** *     ***   * ********   * *  *  **  ****** **  *   of %.2fx^2 + %.2fx + %.2f = 0 are complex and  *** *  ** =     *** *  * =    **  *   * a, b, c, (-b)/(2*a), *  ** ** * (-b)/(2*a),  *    * **  
 * ** *  ** **** *  ** ***     
 *   * ** *  ***  ****   ***** ****  if(d==0) {
 **** ** *  **  *   ***     * *    *   ***  **** * * **** *  **      
 * *  * *** *  **  * ****** *  * *  *  ***      *  *  **     **** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 =  * *** ** a, b, c, x1);
 *****  * *   ***    ***  
 *** *** * ** ****    ***    *      ** ** {
*  *  **   **  ** ** * ***  ** * *  *** * * * *  * *    ***** 
   *** *   ***** ** ** *  ** * **       **      *****    *   **  * 
* *   *  ***  *** ****  ** * ** **   **  **   *       *** *     * * *  of %.2fx^2 + %.2fx + %.2f = 0 are real and    *   *  = %.2f\nx2 =  ** * *  *  a, b, c, x1, x2);
*  ******* ** **  ***** 
}

answered Nov 2, 2017

LinJingYao · Answer 2 · 2017-10-29 01:00:17

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

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

answered Oct 29, 2017 by LinJingYao (-498 points)

LinJingYao · Answer 3 · 2017-10-29 00:56:09

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

int main()
{
  ***   ** *****  ***  *  * *   *   **** ***
 **  * *** *  * * **** ** *    *   *  *   **     * %f     *** * ******  ***  **  **** **
*       ** * *   ***  *       * *   *** 
 *    ** ** * **   *       ** * *   *  ** *
* * * ** **  *** ** **  * **  *** *  *
*  *    * **  * *** * * *  *  *    
    **** **   *   **** * *    * ** **     of %.2fx^2 + %.2fx + %.2f = 0 are real and   *  ***  = %.2f\nx2 =    *  *   **** ** *
***  *** ** ** *  * *  *   *    *   
 * * **  *  * *     * ****   ** *   ** *** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = *** *  *****  * 
 *       *    * *   *** *  *** **
***     ** **   *   ** ** **  ** **** of %.2fx^2 + %.2fx + %.2f = 0 are complex and        **  = %.2f +   *   = %.2f -  * * *** *          *  *  *  *  *  * *       * *
 * *  * *    *  **   ** ***     0;
}

answered Oct 29, 2017 by LinJingYao (-498 points)

coach · Answer 4 · 2017-10-28 22:32:45

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

answered Oct 28, 2017 by coach (-258 points)

coach · Answer 5 · 2017-10-28 22:29:11

Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include<math.h>
int main()
{
*     * *  *  ** *     *   * ** a,b,c,x1,x2,D;
 ***    ** * **      ***** * *      *** %f **  ** **  * *   ** *****
 ***   ** *****  ** **     *****       *
     * *** ** *    *    *  **** = (-b + sqrt(D))/(2*a);
* * * ****  * *  *  * **  ***** = (-b - sqrt(D))/(2*a);
** ********    ****  ***      * *  
***   *  * ***** *   *    *    **    ******  *    *  **   
* ***   *** **  *** ***  ***** ***  * * ** **  ** **        *  **     *  ** * *** * of %.2fx^2 + %.2fx + 1.00 = 0 are real and different\n",a,b,c);
*  *** ** *   *  * * * **** *     * *** *****       ** *  ** ** **  *     ****** *   *** = %.2f\n",x1);
  * * * **       ** *****   **  * *** ***  ** *      *****      * *   *  ** *     *  ** *   * = %.2f",x2);
*** * * *   *   ***  ** * **  ** * * **  * *** **** * *** *** 
 * ***  **     * ** **  ** *  if(D==0)
*  ** *  *  * * *****     **  *  * *  ** *** ** ***
 * *  **   ***   **   **** * *   *** ** * ** * * **  ***   *** ** *** ** **  *         ***      * of %.2fx^2 + %.2fx + 1.00 = 0 are real and same\n",a,b,c);
*   ** **  * *    *   *   *  **   *********  ***  **** * * * ****  ***  * *** * * * * * *  = x2 = %.2f",x1);
   * *  **     ***    ****   **   ****  *  *** *  * ** ***   *
***    * ** **  *  **    *** 
* *   * * *  ** **  **   **  * *  ****  *  ***   * 
**  *  ***  * *  ** * *   * *    * ** ** *  **   **** *** *** * *  * *  *** *  *** *  ** * ** * of %.2fx^2 + %.2fx + 1.00 = 0 are complex and different\n",a,b,c);
 *    * * *** *  ***     * *  ** ** **   ****    *  * * ***        ** ** ****  *** ****  ** = ** ** ***  ** * * **  ***  
 *  * **       **     *  ** *  **  ***     ***    * * ** ****  *    * ****  *    ***** * =  *   * ** *** *****  *  *  * 
**  *   * *    *  *** ** **  **** *****   **    
 **    ** *  *    **      ** * 0;
}

answered Oct 28, 2017 by coach (-258 points)

prog.c: In function 'main':
prog.c:13:20: warning: too many arguments for format [-Wformat-extra-args]
             printf("Roots of %.2fx^2 + %.2fx + 1.00 = 0 are real and different\n",a,b,c);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.c:19:20: warning: too many arguments for format [-Wformat-extra-args]
             printf("Roots of %.2fx^2 + %.2fx + 1.00 = 0 are real and same\n",a,b,c);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.c:24:20: warning: too many arguments for format [-Wformat-extra-args]
             printf("Roots of %.2fx^2 + %.2fx + 1.00 = 0 are complex and different\n",a,b,c);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

commented Oct 28, 2017 by The Judge (4.3k points)

fung2004067 · Answer 6 · 2017-10-28 19:52:22

Hidden content!
 **  *  *   * *  ***
*  **  *   * * ***     
int main()
{
   *** ***  ******** *  * *    *** a,b,c,D = 0,x1 = 0,x2 = 0;
 ** ***** * *   ** **** *  * **     *  *        *   * *   ***  * * * ***    

*   *** * ***  *     *  ***  *   **   ** *  of %.2fx^2 + %.2fx +%.2f = 0  ***  * **** 
  **  ***  ** *   **   * * * = (b*b-4*a*c);
 * * **   ** * ** * * * **  (D < 0)
 ** * *** ** *** *  *    *****
* * *** **  ***  *     ****   *  * * **   complex and   ** ***** *   
 *  * *    * ** *      *   *  *  *   *  = *       * * *   ** ** * ** *** **
 ****  *  *  ** ** **  * **** **** * * **   = **  *****      *  * ***  ** * *
     *  *   * ****  ** **  
 **    * * ** *  *****   * ***  (D > 0)
  *   * *   * ** ******  
*    ******   **  * * *   *  ***  *****   real and ** *****  **** ** 
** *****    * ** ***   *     *  **   * * =     *** ***      + sqrt(D))/(2*a));
** *      * * * * ******    ******* ***  ** = %.2f",(-b - sqrt(D))/(2*a));
*     *  *   *  ** *     **  *   
*        * **  *** * *     (D == 0)
*   **   **  *  *  *  * * ***   
* ** ***  * **     *    ** * ******    *   real and same\n");
***  **  **  ** *** * **     *** *  *  = x2 = %.2f",(-b + sqrt(D))/(2*a));
 *  ** ***    * **  * * *   
}

answered Oct 28, 2017 by fung2004067 (-214 points)

fung2004067 · Answer 7 · 2017-10-28 19:51:44

Hidden content!
****   ** * **  * * 
*   * ****  **  *  * *
int main()
{
 * **        * ** * ** **   * a,b,c,D = 0,x1 = 0,x2 = 0;
  ****   *  * **  ** * ***   *   ****   ***   ***  *** *  ** **  * *   *

 **  ***** **** ** **  ** ****** ******  * *    of %.2fx^2 + %.2fx +%.2f = 0   ***  *  ** *  **
 ** *  * **     * * * *  = (b*b-4*a*c);
  * *** **    ** *   **      ** (D < 0)
***   ** **** **  ***** * **** *
  ** * * **   **  ******  *******  complex and  *    * *  *    **
  * *** *     *  * **   **  **  ** =  *    * * *  * **   * * * * ** * *
* **** **   ** *** ** **  *   ***  * *   =   *****  ** ** **  ***** ** * * * 
   * ** *    *    *  *   ***   **
 * * ***   *  **     *  * * **  (D > 0)
  **** * * **   * ** ** *   * * 
***   *** * *  * *   *    ***  **  * ****    **   real and **   ** * **
**  *** **** *   ******    ** *** ** *   *     =  *** *** **  ** + sqrt(D))/(2*a));
**  **  * * *****  *** * *  * * *     *   = %.2f",(-b - sqrt(D))/(2*a));
*** *  * ********   *** **
*   * **       **    *** * ****   (D == 0)
* **  *   *** *     ****   
*  **** **   ****      * ****   **  real and same\n");
* *  * ** * *  *    *      * **  *   * *** = x2 = %.2f",(-b + sqrt(D))/(2*a));
*  *  **  *  **** ***   *  *
}

answered Oct 28, 2017 by fung2004067 (-214 points)

fung2004067 · Answer 8 · 2017-10-28 14:26:09

Hidden content!
******   *  *     
*** *   * **  **  *  *
int main()
{
*    ***** **   * ******* *** a,b,c,D = 0,x1 = 0,x2 = 0;
 **  ******  * ***     * *  *      ** * ** * * * *  * *  ***   **

 **  * *   ***     *       * * * *****  ******   of %.2fx^2 + %.2fx +%.2f = 0   * *  *  *
      *  * ***   ** *     ** ****  = (b*b-4*a*c);
***   *  * ** ** *   ** **  * (D < 0)
   * *** * *  * * ** *   *** 
 *  **  *  * *   ** *  ***      ****  complex and ******  * *   
  *  * * * ** **   ** * * * **    =  ***   * ** *****  **    * **  * *** *  
 *    * ** ** *** ****      * * **  * *   *   =           * ***** ******* * * ** *
      ** *  * *  * ***   *** 
*      *   **  ******** *   ** * (D > 0)
*  ****   *  ** ** * ***
* * **  * *   * * * * * ****  *    real and *   * *  ***   ** 
 **   *****  **** ****    ** **     ***  = *  **     ** ** + sqrt(D))/(2*a));
*   * * **  ** **   *     **    *** ** * * = %.2f",(-b - sqrt(D))/(2*a));
 *   **   * *** *    ** ***
  * * **** *** ***    **  ***** (D == 0)
 *** ****   **   *  * *  * *
*** *  *   * ******  *    ** * *  ** real and same\r\n");
***  **** **    ** **   *     *  *** *  = x2 = %.2f",(-b + sqrt(D))/(2*a));
*** * ******* * *  * **** * 
}

answered Oct 28, 2017 by fung2004067 (-214 points)

fung2004067 · Answer 9 · 2017-10-28 14:25:06

Hidden content!
***** **** ***  ** **
** *     *  * *  * **
int main()
{
* ****    * *    * *  * ***  a,b,c,D = 0,x1 = 0,x2 = 0;
      *  **** *****  *       ** * * ** * ** ***    ** * *  *   ** * **

  *** **** * * * *** * * * **  *     *    of %.2fx^2 + %.2fx +%.2f = 0   *  * ** ** *    * 
**    *  * ** * * *    * **  ** *** = (b*b-4*a*c);
 **  * * **  ** * ****   * (D < 0)
**  * ***** **  *   ****** **  
*  *** ***  ** ** **** *    ** ***  **** complex and   *** ****  *
*  * * * *** *  *** *** *   *      *  **   =  * **  *  ***  ****   *  **  *   ** 
**** *  *******  *   *** ** * ****    ***** =  * *    **       *  * *  *    *
 **  **         * ** ** ** * 
 *  * ****   *** ** * * * *     (D > 0)
  **** *  ****    *  * *  * *
** ***   *  * * *  *     **  *      * real and  * *   *** * *** 
    *** *****       *    ****  ** *       =    ***     *  + sqrt(D))/(2*a));
 * *  * * *   ******   **** * **  *** *  = %.2f",(-b - sqrt(D))/(2*a));
**         ** ***** ** ** * *
****      **     ** * *   **  *  (D == 0)
** *** *   ****** ***   * ** 
**  **********   **   ** *  ****   *** ** real and same\r\n");
*   *    * *   *       *  ***    ***       *   = x2 = %.2f",(-b + sqrt(D))/(2*a));
***** **** *  *  ** **** *** ***
}

answered Oct 28, 2017 by fung2004067 (-214 points)

fung2004067 · Answer 10 · 2017-10-28 14:22:54

Hidden content!
  ********  * *  ** ***
    *  ***** ****   
int main()
{
 ******  ** * *  * * **  * ** a,b,c,D = 0,x1 = 0,x2 = 0;
***** * **   *  *  *  *    *      *   *** ** *    * ***  ********  

 * ** ********** **     ***    *  **    ***  of %.2fx^2 + %.2fx +%.2f = 0 are",a,b,c);
* **        ** *  ** * *  = (b*b-4*a*c);
*   * **** **** * *  *  ** * = (-b + sqrt(D))/(2*a);
 * *** **** *   * *    * ** *    **  = (-b - sqrt(D))/(2*a);
 *    ** **   ** *         *  ***  (D < 0)
* * *******  ****      **** 
 * * * * *     ** *   * ** * * ** * * *    * * complex and *  * *** * * * 
 ** * *  *   *     * *** *     * **  ** = ****  *  * **** *** ** ****    * ***
     *** *  ** **   *   * *  ** *    *  =   *****   **  **  *  * ** *   * 
***   * ***  * *  ** * **  
  *  * **** *  * * ** *   *    (D > 0)
***** *  *** * ** ****** * 
** *     *  *  * *  ****   *** ***    * real and  **  *  *  **    **
*** *   *********           * **  *****  = **   *  *   **
*       ** * ****    *    * * ** *****  = %.2f",x2);
******  *    *  *    * *** *** * 
 *  ** *  * * **     *  *** *  * (D == 0)
 **  ** * *   ** *     *   **
 * ** *  *   **    ***** * ** *     ***** real and same\r\n");
*  *   *    *   *  **** *    **** * *    *  = x2 = %.2f",x1);
    * ******  *** * ****    
}

answered Oct 28, 2017 by fung2004067 (-214 points)

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