(5又1/4)²-(3又3/4)²简便方法计算199²+1+2x199
问题描述:
(5又1/4)²-(3又3/4)²简便方法计算
199²+1+2x199
答
(5又1/4)²-(3又3/4)²
=(5又1/4+3又3/4)(5又1/4-3又3/4)
=9 *3/2
=27/2
199²+1+2x199
=(199+1)²
=200²
=40000