简便运算2009x2008分之2007.

问题描述:

简便运算2009x2008分之2007.

2009*2007/2008
=(2008+1)*2007/2008
=2008*2007/2008+1*2007/2008
=2007+2007/2008
=2007又2008分之2007

原式=(2008+1)×(2008-1)/2008
=(2008×2008)/2008-1/2008
=2008-1/2008
=2007又2007/2008