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

Question

7.9k 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 | 7.9k 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