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>
***   ***    *  *
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

Hidden content!
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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

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

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