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

Question

15.1k 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 | 15.1k 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