2020-07-04

//求二次方程 /* using System;namespace _2 { class Program { static void Main(string[] args) { double x; double y; Console.WriteLine(""); x = double.Parse(Console.ReadLine()); y = x * x + 3 * x - 5; string str = String.Format("{0:N3}", y); Console.WriteLine(str); Console.ReadLine(); } } }