0 like 1 dislike
17.3k views

Write a program to find roots of a quadratic equation

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 in Chapter 5: Selection Statements by (5.2k points)
ID: 28934 - Available when: 2017-10-26 18:00 - Due to: Unlimited

reopened by | 17.3k views
0 0
We will continue this question in few days
0 0
Everything is fixed. Enjoy your time with The Judge :)
0 0
ANNNNNNNNNNNNNNNNNNNNNNNNNNGRYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY
0 0
Your code has newline at the end sometime. You learned this lesson many times!
0 0
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.
0 0
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

56 Answers

0 like 0 dislike
Hidden content!
#include <stdio.h>
* * ** ** * *
int main()
{
* * * ** ** ** **** * ** * ** **** **
* * * ** * **** ** * * **** %f *** * ** * * ** *
*** * ** * * * = (b*b-4*a*c);
* *** *** ** ** ** * = (-b + sqrt(D))/(2*a);
** ** * * ** *** = (-b - sqrt(D))/(2*a);
**** * ***** ** ** * * * ** = -b/(2*a);
* * * * ******* ** ******* * ** * =sqrt(-D)/(2*a);
* * ******** * ** *** * *
* ** ** * **** **
* * ** * ***** **** * * *** * * * * ** ***** * *** *** *** *** of %.2fx^2 + %.2fx + %.2f = 0 are real and ***** * * *
** ** * * **** * ****** ***** ** * * * **** * * * *** * = %.2f\nx2 = %.2f",x1,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 * *** * * ** *
* * * * ** * * ** * * * *** * **** * * *** = ***** * ***** **** * ***
* ** *** * ** * * * * ************ **** ** *** * ** * = * * ** ** ** * **
******** * * **********
* * * * *** * ** *** 0;
}
answered by (-281 points)
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output
0 like 0 dislike
Hidden content!
#include <stdio.h>
* ** * ** ** * **
int main()
{
* ** * * * * * ** * ******* ****** * *
* * ** *** **** **** * * *** * * ** %f * * ** * * ****** *
* * *** * * * *** * * = (b*b-4*a*c);
*** * * ** * ** *** * * = (-b + sqrt(D))/(2*a);
** *** * *** ***** = (-b - sqrt(D))/(2*a);
* * * ** * * ***** ** * *** ** = -b/(2*a);
*** *** *** * * * * **** ** ** =sqrt(-D)/(2*a);
* * * *** * *
* ** * ** * * * **
* *** * * *** * * *** * * ** **** ** *** ** * ** of %.2f x^2 + %.2f x + %.2f = 0 are real and ******** * * * * ***
** * *** ** *** ** *** * * ** ** * * *** = %.2f\nx2 = %.2f",x1,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 * * * * * * *
**** * * * ** * ** ** * * ** * * * * * **** ** * * * * * = ***** * ** ** * ** * * * *
* ** *** * *** * ** * *** * ** * * * * * = * ** ** * ** ** ** *
*** * * ** ** * *
******* * * ** ** * * * *** 0;
}
answered by (-281 points)
0 0
Case 0: Correct output
Case 1: Wrong output
Case 2: Correct output
Case 3: Wrong output
0 like 0 dislike
Hidden content!
#include <stdio.h>
#include <stdlib.h>

int main()

{
* ** * * **** * *** * a,b,c,x1,x2,D=0;
* ** ******* * *** * *
*** ** ** ** ** * ** **** %f *** * * ** ** * *** * ** * *****
**** * * **** * ** *
* ** * * **** *** * ** *** **
* * ***** *** ** * * * ** ** + sqrt(D))/(2*a);
** * * *** **** * * ** - sqrt(D))/(2*a);
* *** * * * * *
** * ** * **** ** * * **** **
*** * * * * ** ** *
* *** ***** ** * *** * *** ** * **** ** * * *** of %.2fx^2+%.2fx+%.2f=0 are complex and **** * ** ** * ** * * **
*** * ***** * * ***** *
* * *** ** *** * ** **
**** *** * ** ** * * * * if(D==0)
* *** *** * * * * ** * *
* * * ** *** **** ** ** * ***** * * ***** ** ** * of %.2fx^2+%.2fx+%.2f=0 are real and same\nx1=x2=%.2f",a,b,c,x1);
* * ** ** ** *** ****
******* * ** * * * *
*** *** * * * ** * *
*** * *** * *** **** * **
* ** * * *** ** *** * * * *** ** * ** * * of %.2fx^2+%.2fx+%.2f=0 are real and ** ** ** * ** * * ** * **
* ** ** ***** * * *** ***
* ** ** *** ***
*** *** * * * ** *** **** *
* * ****** * ** **** * ** * 0;
}
answered by (-127 points)
0 0
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'
0 like 0 dislike
Hidden content!
** ** ****
int main()
{
* * ** **** * * * *** * ** * * ** a,b,c,D;
* * * * ** * ** * * x1,x2,r,i;
* * * * * * ** * ** *** * * **** ** * * * **** *** * ** * *** *
*** * ** * ** * ** **** *
***** * *** ** ** * * * **
* * **** ** * * ** ** * * **** ** *
* * ** ** * ** * * * * * *
* ** ** **** *** * ***
*** * ** *** * **** * * * * ** * *** ****** ** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",a,b,c);
** *** ** ** *** ****** ***** * * * ** ** ** * ** * * * * *** * = x2 = %.2f",x1);
** ** * ** ** * * **
* *** * * * * ** ** ** * * if(D>0)
* *** * ** * * ** **
* ** * * *** ** * * ** ** * * ** **** ***** *** ** * of %.2fx^2 + %.2fx + %.2f = 0 are complex and * * *** * ****** *
** ****** * * ***** ** ** **** * * * * * **** * * * = %.2f\n",x1);
* * ** * * * * * * **** * * ** *** ** * * * * = %.2f",x2);
** ** * ** ** ** *** * *
* *** * ** ** ** * if(D<0)
** * *** ** * * * *
* ** ****** ** ** * * ** * **** * ***** **** ** ** * **** * of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\n",a,b,c);
* **** * * * * * * ** *** * * *** *** * ** * -b/(2*a);
* ** * * * * * * * * * *** *** ****** **** ** *
** **** ** * ** *** * * ** ** ** ** = %.2f+%.2fi\n",r,i);
* ** * *** *** * ** * **** ** * * ***** *** **** * = %.2f-%.2fi",r,i);
***** * * *** * ****
}
answered by (-329 points)
0 0
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'
0 like 0 dislike
Hidden content!
* * ** * * * **
int main()
{
* * * ***** ** * **** a,b,c,D;
** ** *** *** ** * * *** **** x1,x2,r,i;
*** **** * *** ** *** * ******* ** * **** ** ** *
* ***** *** *** ** * **** **
* * * * * * * ** ** * ** ** **
*** * ***** * ** * * ***** * * ** ****
* ** * * * *** ******* **
* **** ** ** * **** *
**** ******* *** * *** * * ***** ** ** * ** * ** ***** * * of %.2fx^2 + %.2fx + %.2f = 0 are real and same\n",a,b,c);
* * **** ** **** * ** **** * * * *** * *** ******** * = x2 = %.2f",x1);
* ** ** ** **** ***
**** * * * * ** ** ** * if(D>0)
* ** *** * * * * ** * ***
*** * ** * *** * *** *********** * *** **** ****** *** of %.2fx^2 + %.2fx + %.2f = 0 are complex and * * * ** ***
* ***** * * ** * * * ****** * **** * * ** * ****** = %.2f\n",x1);
**** * ** * *** * *** * ** * * ** * * *** * *** = %.2f",x2);
*** * ****** **** * *
* ** *** * ** * ** *** if(D<0)
* * *** * ** *** *** * * * *
** * ***** * * **** * * * * * ** * * *** of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\n",a,b,c);
** * **** ** * * * ** * *** * * * ** -b/(2*a);
* ******* * ***** *** * * ** * ** * * * * * ** *
** ** ** * ** ** ** * * ** * * * * ** * * ** = %.2f+%.2fi\n",r,i);
** ** ** *** ** **** **** ** **** **** * **** ** * * * = %.2f-%.2fi",r,i);
* * * * ** * *
}
answered by (-329 points)
0 0
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'
0 like 0 dislike
Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main()
{
*** * * * * * * ** **** ** * a,b,c,d,x1,x2;
** * * * ** ****** ** * *** * ** ** * *** ** * * * *
* * *** **** * * * * **
* ** ***** * ** * ** *** * **
** * * ** ** ** * * * ** ** *** * ***
** ** ** * ** ****** * ***
* * ** ****** * * ** ***
*** * * * * ** ****** * ****** * ** * * *** ** of %.2fx^2 + %.2fx + %.2f = 0 are real and * * ** * ** *
** **** ** * *** *** * * *** * *** ** * * ** * = %.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 ** * ** ** * * ***
* ** ** ****** *** * * * *** *** * * * *** * = ** * * *** * * *** * *** *
* **** ******** * * * * **** * * **** = * ****** * * ** *
*** *** ** ** ** ** *
* ***** * * *** * 0;
}
answered by (-498 points)
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output
0 like 0 dislike
Hidden content!
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
* * * * * * ** *** **** a,b,c,d,x1,x2;
** * * * * ** * *** * ** * **** ** ** * ***
* ***** * * ** *** * ***
** **** ** ******* = (-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 by (-108 points)
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output
0 like 0 dislike
Hidden content!
#include ** * **** **
#include * * *

int main()

{
* ***** *** * *** * *** *** * *
* ***** ** * * * * * *** *** * %f * ***** ** * * * * ** ***

* ** **** * * ** **** * **** **
*** * * ***** ** * * **** * + sqrt(D))/(2*a);
**** * ** ** * ** * * * * - ** ***
*** * *** * ** **** *** ** * *
* ** * *** * **** * ******* *** * **

* **** *** ****** * * *** (D==0)
*** *** * ** * * ** **
** * **** * * *** ** ** * ** *** * *** * *** * ** * *** of %.2fx^2 + %.2fx + %.2f = 0 are real and same\nx1 = x2 = * ** ** * * *
* ** ** ** ** * * **
**** *** ** * if (D>0)
**** ** ** ** * * *
*** ** *** ** * ** * * * ** * ** **** **** * * * * of %.2fx^2 + %.2fx + %.2f = 0 are real and different\nx1 = %.2f\nx2 = * * * ** * * *
*** ****** ***** * * *** *
**** * ** ** * *** * **
* * ******* * * * *** ** **
** * * * * ****** *** ** **** ** * * ***** ***** ** * * * of %.2fx^2 + %.2fx + %.2f = 0 are complex and different\nx1 = %.2f+%.2fi\nx2 = ** * * *** * * ** *** * ***
** * ** ***** ** ** **

*** **** ** ****** ** * 0;

}
answered by (-249 points)
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output
0 like 0 dislike
Hidden content!
#include * * *** **
#include * * * ***
int main(void)
{
float a,b,c, D, x1, x2,i;
** ** * *** ** *** *** ** * * *** * %f ** *** &a, &b, &c);
* * * **** * * *** ** *
* * * ** * ** * (D>0)
**** *** * ** * * **
* **** **** **** * **** **** **** * **** * * *
** * ** ** * *** * ****** ** ****** *** * ** * * * **

* * * *** ** * **** * * * *** * *** * * * * * * ** * * * * ** 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 = *** * **** * *
* * * ****** ** ** **
** ** ** ** * ** ** * **
** * *** * ** ****
** * * * ** **** **** **   x1=x2 = -b/(2*a);
*** ** *** * ** * ***** ** * * * *** * ** * *
** * * ** * * ** ** ** ** * * * * * *** ** *** of %.2fx^2 + %.2fx + %.2f = 0 are complex and * ***** = * ** *** = **** ** * ** x2,i);
* * *** * ** ****



* *** * ** * ** 0;
}
answered by (-304 points)
edited by
0 0
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'
0 0
Case 0: Correct output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output
0 0
prog.c: In function 'main':
prog.c:21:5: error: expected ';' before '{' token
     {
     ^
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Wrong output
Case 3: Correct output
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output
0 like 0 dislike
Hidden content!
#include **** * * **
#include * **** * **** *

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


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


** ** ** *** ** * * ** * * * = b*b-4*a*c;

* *** * ** * * *** * *** 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;
}
answered by (-167 points)
0 0
Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output
Welcome to Peer-Interaction Programming Learning System (PIPLS) LTLab, National DongHwa University
English 中文 Tiếng Việt
IP:104.23.243.77
©2016-2026

No related questions found

12,783 questions
183,442 answers
172,219 comments
4,824 users