张春年老婆:五年级奥数题
来源:百度文库 编辑:查人人中国名人网 时间:2024/05/11 17:15:50
假设2n个小朋友,n个小朋友只有1元的钞票,另外n个小朋友只有2元的钞票,种数S,
当n=1时,S=(2*1)!/2=1;
当n=2时,S=(2*2)!/3=8;
当n=3时,S=(2*3)!/4=180;
当n=4时,S=(2*4)!/5=4032;
......
一般规律为S=(2*n)!/(n+1),
所以,当n=5时,S=(2*5)!/6=10!/6=604800种。
http://www.baidu.com/s?wd=%D3%CE%C0%D6%D4%B0%C3%C5%C6%B11%D4%AA1%D5%C5%2C%C3%BF%C8%CB%CF%DE%B9%BA1%D5%C5.%CF%D6%D4%DA%D3%D010%B8%F6%D0%A1%C5%F3%D3%D1%C5%C5%B6%D3%B9%BA%C2%F2%2C%C9%ED%C9%CF%D3%D01%D4%AA%BB%F22%D4%AA%B5%C4%D0%A1%C5%F3%D3%D1%B8%F7%D3%D05%C8%CB%2C%CA%DB%C6%B1%D4%B1%C3%BB%D3%D0%C1%E3%C7%AE.10%B8%F6%D0%A1%C5%F3%D3%D1%2C%B2%BB%CD%AC%B5%C4%C5%C5%B6%D3%B7%BD%B7%A8%D3%D010%21%3D3628800%D6%D6.%CE%CA%3A%D3%D0%B6%E0%C9%D9%D6%D6%C5%C5%B6%D3%B7%BD%B7%A8%2C%CA%DB%C6%B1%D4%B1%D7%DC%C4%DC&cl=3
假设2n个小朋友,n个小朋友只有1元的钞票,另外n个小朋友只有2元的钞票,种数S,
当n=1时,S=(2*1)!/2=1;
当n=2时,S=(2*2)!/3=8;
当n=3时,S=(2*3)!/4=180;
当n=4时,S=(2*4)!/5=4032;
......
一般规律为S=(2*n)!/(n+1),
所以,当n=5时,S=(2*5)!/6=10!/6=604800种。
顶`