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

Question

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

Comments

We will continue this question in few days

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Everything is fixed. Enjoy your time with The Judge :)

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ANNNNNNNNNNNNNNNNNNNNNNNNNNGRYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

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Your code has newline at the end sometime. You learned this lesson many times!

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After i correct the newline in my code,there is still wrong output.However,I had run the program in Codeblocks.The output is still as well as the result. Seeking for help.

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your output lack of 1 space at line 8 when print out "Roots of ...". Please be careful with all small details when working with online judge

Answer 1

Hidden content!
#include <stdio.h>
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Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 2

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int main()
{
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Comments

Case 0: Correct output
Case 1: Wrong output
Case 2: Correct output
Case 3: Wrong output

Answer 3

Hidden content!
#include <stdio.h>
#include <stdlib.h>

int main()

{
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}

Comments

prog.c: In function 'main':
prog.c:12:14: warning: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
     x1=(-b + sqrt(D))/(2*a);
              ^~~~
prog.c:12:14: warning: incompatible implicit declaration of built-in function 'sqrt'
prog.c:12:14: note: include '<math.h>' or provide a declaration of 'sqrt'

Answer 4

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{
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}

Comments

prog.c: In function 'main':
prog.c:6:5: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
     scanf("%f%f%f",&a,&b,&c);
     ^~~~~
prog.c:6:5: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:6:5: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:12:9: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",a,b,c);
         ^~~~~~
prog.c:12:9: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:12:9: note: include '<stdio.h>' or provide a declaration of 'printf'
prog.c:17:9: warning: incompatible implicit declaration of built-in function 'printf'
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\n",a,b,c);
         ^~~~~~
prog.c:17:9: note: include '<stdio.h>' or provide a declaration of 'printf'
prog.c:23:9: warning: incompatible implicit declaration of built-in function 'printf'
         printf("Roots of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\n",a,b,c);
         ^~~~~~
prog.c:23:9: note: include '<stdio.h>' or provide a declaration of 'printf'

Answer 5

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int main()
{
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}

Comments

prog.c: In function 'main':
prog.c:8:12: warning: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
     x1=(-b+sqrt(D))/(2*a);
            ^~~~
prog.c:8:12: warning: incompatible implicit declaration of built-in function 'sqrt'
prog.c:8:12: note: include '<math.h>' or provide a declaration of 'sqrt'

Answer 6

Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main()
{
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}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 7

Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
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}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 8

Hidden content!
#include * * ** *    ** * 
#include   * *  * ***** *

int main()

{
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}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 9

Hidden content!
#include *** *  *   * 
#include   *  *  * ** **
int main(void)
{
float a,b,c, D, x1, x2,i;
**   ***** ******  * ** *  *********   %f *  **   &a, &b, &c);
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*** ** **      * *   ** ** *     * 0;
}

Comments

prog.c: In function 'main':
prog.c:10:16: warning: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
         x1=(-b+sqrt(D))/(2*a);
                ^~~~
prog.c:10:16: warning: incompatible implicit declaration of built-in function 'sqrt'
prog.c:10:16: note: include '<math.h>' or provide a declaration of 'sqrt'

---

Case 0: Correct output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

---

Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output

---

Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output

---

prog.c: In function 'main':
prog.c:21:5: error: expected ';' before '{' token
     {
     ^

---

Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output

---

Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output

---

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 10

Hidden content!
#include   * *        
#include  *    ***  ** 

int main()
{
**  * **   ***    *  * *** a, b, c,   *  * * x1,x2, realPart, *  *   ** 


*  ** *      *  *   *  * * *** ***   ** *   **** %lf * **     *        &b, &c);


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 * *  **  *   *** *** *     condition for real and different roots


 *     * **   *****  ** *  * * * for real and equal roots
*** *        *** **  ***    * *   (determinant == 0)
* **   *    * *  * * ** 
* *  *  * * * **      ********* ** ***   *  ** *    *   ** * = x2 = -b/(2*a);
       **   **  *** *  *  *  *  ** * *  * ** ****** * * **** *  *** of %.2fx^2 + %.2fx + %.2f = 0 are real and  *   *****  a,b,c);
*   * * * *   **** *    * * **    *  * **  **   *  ***   ***    = x2 = *****   x1);
  * *    *** **** ***  **   *

** **   **   *****   ******  **   if (determinant > 0)
 ** * *       *    * *  
****  * *   ****  **  ***  sqrt() function returns square root
  *   *      ****** *  *  ** *  **** ***       ***** *   = **   *     * *** ** *
***    ** **   **     * *   ** * **  *   ***  *  * = * *       *   **

*** ** ** * * ******  * *******  *****  * * *   ***** * * *  * *** * ** *   * of %.2fx^2 + %.2fx + %.2f = 0 are real and   * **  **  *  * **
**  ***  **     *   **  ****     *   ** *  **     **  *  **  =  **  *   x1);
* * *** ******  *****  **** ***** **  ******** * *    **    **  *    =      **     ** x2);
*  ** ***** **     *    ** **  if roots are not real
*   * *** *** * * *      
  *   ** *** * ** **** *  **
**   *   ****   *  **  ***  **  ***  ** **      * ** * = -b/(2*a);
 *******    * ***  ****** *** * * * *** **** ** * *  **  * *  *** ***  = * * ** ****  ** 
* *  * *****     * *  **  *   ** **  ****  *  **   ** *  ****      *  *     **  of %.2fx^2 + %.2fx + %.2f = 0 are complex and ****  * *****    * a,b,c);
**** **  *** **   ******** *  *      * ******     * **** * *   = ** ** *    **   ** realPart,    ** **
****** ***********   ** * **** **   * *  *  **   ****   * **** =    * *  ****       realPart, * ** ***
  **   ******   **** *  *

***  *  **** ****   *        0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output