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

Question

12.1k 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 | 12.1k 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