anyone who can help me fix this c++ code,kindly? It was to solve the real roots of a quadratic equation.

Question

#include <iostream>
#include<cmath>

using namespace std;

int main()
{
//quadratic eqn is in form of a*a + 2*a +c
// our a*a will be unknown_a
//our 2*a will be unknown_b
//our c will be num_c

double unknown_a, unknown_b, num_c, real_roots,real_root2;
cout << "enter the first unknown" << endl;
cin >> unknown_a;
cout << "enter the second unknown" << endl;
cin >> unknown_b;
cout << "enter the third value(C)" << endl;
cin >> num_c;
real_roots=- unknown_b+ ( sqrt((unknown_b*unknown_b)-(4*unknown_a*num_c))/2*unknown_a);
cout << "root one is:";
cout << real_roots<<endl;
real_root2=- unknown_b-( sqrt((unknown_b*unknown_b)-(4*unknown_a*num_c))/2*unknown_a);
cout << "root two is:";
cout << real_root2;

return 0;
}

Answer 1

The parentheses in your formula are wrong. Recall that the quadratic polynomial is:
ax²+bx+c

And its real roots are:
x=(-b±√(b²-4ac))/2a

Also, the 'unknowns' are not really unknowns when the user inputs them 😛

Answer 2

Your intention is to divide by 2a, but order of operations causes it to divide by 2 and then multiply by a.

As Giorgos D indicated, it can be fixed by using parentheses that force the order of operations. Replace /2*unknown_a with /(2*unknown_a).

Answer 3

This will help you if you like it to analyze:

https://code.sololearn.com/c079doXhZlMI/?ref=app