[解答] 計程上機考Q7

[wendychang (柯南42真是妙)]

#include <stdafx.h>

#include <iostream>

using std::cout;
using std::cin;
using std::endl;

#include <iomanip>

using std::fixed;
using std::setprecision;

#include <cmath>

int main()
{
        float a, b, c, D;
        float a, b, c, D;
        cout << "請輸入一元二次方程式係數a : ";
        cin >> a;
        cout << "請輸入一元二次方程式係數b : ";
        cin >> b;
        cout << "請輸入一元二次方程式係數c : ";
        cin >> c;
        cout << endl;

        if ( a==0 )
        {
                if ( b==0 )
                {
                        if ( c==0 )
                                cout << "x無限多解" << endl;
                        else
                                cout << "x無解" << endl;
                }
                else
                        cout << fixed << setprecision( 4 )
                                 << "x = " << -c / b << endl;
        }
        else
        {
                D = b * b - 4 * a * c;

                if ( D > 0 )
                        cout << fixed << setprecision( 4 )
                                 << "x = " << -b / ( 2 * a ) + sqrt( D )
                                 << " , " << -b / ( 2 * a ) - sqrt( D ) << endl;

                else if ( D == 0 )
                        cout << fixed << setprecision( 4 )
                                 << "x = " << -b / ( 2 * a )
                                 << " , " << -b / ( 2 * a ) << endl;

                else
                        cout << fixed << setprecision( 4 )
                                 << "x = " << -b / ( 2 * a ) << "+"
                                 << sqrt( -D ) / ( 2 * a ) << "i , "
                                 <<-b / ( 2 * a ) << "-"
                                 << sqrt( -D ) / ( 2 * a ) << "i" << endl;
        }
        cout << endl;


        return 0;
}

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