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

Question

9.4k 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 | 9.4k 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