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

Question

6.6k 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 | 6.6k 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