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

Question

7.8k 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 | 7.8k 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