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

Question

9.7k 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 | 9.7k 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