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

Question

15k 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 | 15k 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