Nguyễn Đình Dũng nói xàm

http://olm.vn/hoi-dap/question/220891.html

A = 2010²⁰¹¹ - 2010²⁰¹⁰

A = 2010²⁰¹⁰ .( 2010 - 1)

A = 2010²⁰¹⁰.2009

2009 ⋮ 2009 ⇒ A = 2010²⁰¹⁰.2009 ⋮ 2009

Nó có chia hết à ??? 

Ta thấy 2009 chia 2010 dư  -1 

=> 2009 ^ 2008 chia 2010 dư 1 (1)

Lại có  2011 chia 2010 dư 1

=> 2011^2010 chia 2020 dư 1 (2)

Từ (1)(2) => 2009^2008-2011^2020 chia 2010 dư 2 (sai )

2009^2008+2011^2010 chia hết cho 2010 2009^2008+2011^2010

=2009^2008+2011^2010

=2009^2008+2011^2010+1-1

=(2009^2008+ 1) + (2011^2010– 1)

= (2009 + 1)(2009^2007- …) + (2011 – 1)(2011^2009 + …)

= 2010(2009^2008 - …) + 2010(2011^2009+ …) chia hết cho 2010  

2009^2008+2011^2010 chia hết cho 2010 2009^2008+2011^2010

=2009^2008+2011^2010

=2009^2008+2011^2010+1-1

=(2009^2008+ 1) + (2011^2010– 1)

= (2009 + 1)(2009^2007- …) + (2011 – 1)(2011^2009 + …)

= 2010(2009^2008 - …) + 2010(2011^2009+ …) chia hết cho 2010  

Lời giải:

Đặt $A=5^0+5^1+5^2+5^3+....+5^{2010}+5^{2011}$

$A=(5^0+5^1)+(5^2+5^3)+....+(5^{2010}+5^{2011})$

$=(1+5)+5^2(1+5)+...+5^{2010}(1+5)$
$=(1+5)(1+5^2+....+5^{2010})$
$=6(1+5^2+....+5^{2010})\vdots 6$

From: exoplanet

To: Nguyễn Ngọc Phương Thảo

\(2009^{2008}+2011^{2010}=\left(2009^{2008}+1\right)+\left(2011^{2010}-1\right)\)

\(=\left(2009+1\right)\left(2009^{2007}+a\right)+\left(2011-1\right)\left(2011^{2009}-b\right)\)