算术平方根sqrt()

#include <bits/stdc++.h>
using namespace std;

int main()
{ 
    double a , b , c , x1 , x2 , d;
	cin >> a >> b >> c;
	
	d = b * b - 4 * a * c;
	
	if ( d < 0 )
	{
		cout << "No answer!" << endl;
		return 0; 
	}
	
	x1 = ( -b + sqrt( d ) ) / ( 2 * a );
	x2 = ( -b - sqrt( d ) ) / ( 2 * a );
	
	if ( d == 0 )  printf( "x1=x2=%.5lf\n" , x1 );
	
	if ( d > 0 )
	{
		if ( x1 < x2 )  printf( "x1=%.5lf;x2=%.5lf\n" , x1 , x2 );
		
		else  printf( "x1=%.5lf;x2=%.5lf\n" , x2 , x1 );
	}
	return 0;
 }

sqrt()