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

Question

7.6k 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 | 7.6k 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