0 like 1 dislike
19.8k 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 | 19.8k 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:104.23.197.95
©2016-2026

No related questions found

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