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>
* *  *  *** * *   **** *   
int main()
{
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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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#include <stdio.h>
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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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int main()
{
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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;
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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