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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Comments

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

Answer 3

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#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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}

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

Hidden content!
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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

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#include *******  ****   **
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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;
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}

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,    **  * **


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** **    **  ****  **   * **  *****      (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