Question

So sánh A với 4

  A = \(\frac{2010}{2009}\)+ \(\frac{2011}{2010}\)+\(\frac{2012}{2011}\)+\(\frac{2009}{2012}\)

   Giai rõ ra hộ mk nha

Answer 1

giải giúp mk với mk đang cần gấp lắm!!! Mong các bạn giúp đỡ mk với!!!

Answer 2

\(A=\frac{2010}{2009}+\frac{2011}{2010}+\frac{2012}{2011}+\frac{2009}{2012}=\left(1+\frac{1}{2009}\right)+\left(1+\frac{1}{2010}\right)+\left(1+\frac{1}{2011}\right)+\frac{2009}{2012}>\left(1+\frac{1}{2012}\right)+\left(1+\frac{1}{2012}\right)+\left(1+\frac{1}{2012}\right)+\frac{2009}{2012}=\left(1+1+1\right)+\left(\frac{1}{2012}+\frac{1}{2012}+\frac{1}{2012}+\frac{2009}{2012}\right)=3+1=4\)Vì 1/2009,1/2010,1/2011>1/2012

Vậy A>4

Answer 3

A=(1+1/2009)+(1+1/2010)+(1+1/2011)+(1-3/2012)

A=(1+1+1+1)+(1/2009+1/2010+1/2011-3/2012)

A=4+(1/2009+1/2010+1/2011-3x1/2012)

vì 1/2009>1/2010>1/2011>1/2012

nên 3x1/2012>(1/2009+1/2010+1/2011)

hay  3x1/2012-(1/2009+1/2010+1/2011)>0

Answer 4

vậy A>4