so sánh : A = 2008 / 2009 + 2009 / 2010 + 2010 / 2011
B = 2008 + 2009 + 2010
—————————- ——->> PHẦN
2009 + 2010 + 2011
so sánh : A = 2008 / 2009 + 2009 / 2010 + 2010 / 2011 B = 2008 + 2009 + 2010 —————————-
By aihong
Đáp án + Giải thích các bước giải:
`A=2008/2009+2009/2010+2010/2011>2008/2011+2009/2011+2010/2011=(2008+2009+2010)/2011>(2008+2009+2010)/(2009+2010+2011)=B`
Vậy `A>B`
Đáp án:
`A>B`
Giải thích các bước giải:
ta có :
`A=2008/2009+2009/2010+2010/2011`
`B=(2008+2009+2010)/(2009+2010+2011)`
`=2008/(2009+2010+2011)+2009/(2009+2010+2011)+2010/(2009+2010+2011)`
ta xét :
`=>` `2008/2009>2008/(2009+2010+2011)`
`=>` `2009/2010>2009/(2009+2010+2011)`
`=>` `2010/2011>2010/(2009+2010+2011)`
nên : `2008/2009+2009/2010+2010/2011>(2008+2009+2010)/(2009+2010+2011)`
`=>` `A>B`