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18 tháng 9 2018

\(B=...=\frac{\left(3-1\right)\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)}{2}=\frac{\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)}{2}\)

\(=\frac{\left(3^4-1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)}{2}=\frac{\left(3^8-1\right)\left(3^8+1\right)\left(3^{16}+1\right)}{2}=\frac{\left(3^{16}-1\right)\left(3^{16}+1\right)}{2}=\frac{3^{32}-1}{2}< 3^{32}-1=A\)

18 tháng 9 2018

Ta có : \(B=\left(3+1\right).\left(3^2+1\right).\left(3^4+1\right).\left(3^8+1\right)+\left(3^{16}+1\right)\)

       \(\Rightarrow\) \(2B=2.\left(3+1\right).\left(3^2+1\right).\left(3^4+1\right).\left(3^8+1\right).\left(3^{16}+1\right)\)

                      \(=\left(3-1\right).\left(3+1\right).\left(3^2+1\right).\left(3^4+1\right).\left(3^8+1\right).\left(3^{16}+1\right)\)

                       \(=\left(3^2-1\right).\left(3^2+1\right).\left(3^4+1\right).\left(3^8+1\right).\left(3^{16}+1\right)\)

                        \(=\left(3^4-1\right).\left(3^4+1\right).\left(3^8+1\right).\left(3^{16}+1\right)\)

                        \(=\left(3^8-1\right).\left(3^8+1\right).\left(3^{16}+1\right)\)

                         \(=\left(3^{16}-1\right).\left(3^{16}+1\right)\)

                           \(=3^{32}-1\)

\(\Rightarrow\) \(B=\frac{3^{32}-1}{2}< 3^{32}-1\)

\(\Rightarrow\) \(B< A\)

25 tháng 9 2021

a) \(A=\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)=\dfrac{1}{2}\left(3-1\right)\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)=\dfrac{1}{2}\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)=\dfrac{1}{2}\left(3^{32}-1\right)< 3^{32}-1=B\)

b) \(A=2011.2013=\left(2012-1\right)\left(2012+1\right)=2012^2-1< 2012^2=B\)

22 tháng 10 2020

a) Ta có : 2005.2007 = (2006 - 1)(2006 + 1) = 20062 - 12 = 20062 - 1 ( cái khúc này sửa : 2005.2001 thành 2005.2007)

Mà B = 20062

=> 20062 - 1 < 20062 

=> A < B

b) Ta có : B = (2 + 1)(22 + 1)(24 + 1)(28 + 1)(216 + 1)

                B =  (2 - 1)(2 + 1)(22 + 1)(24 + 1)(28 + 1)(216 + 1)

                B = (22 - 1)(22 + 1)(24 + 1)(28 + 1)(216 + 1)

                B = (24 - 1)(24 + 1)(28 + 1)(216 + 1)

                B = (28 - 1)(28 + 1)(216 + 1) = (216 - 1)(216 + 1) = 232 - 1

Mà C = 232

=> B < C 

c) Tương tự như câu b

12 tháng 9 2021

\(\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)=\dfrac{1}{2}\left(3-1\right)\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)=\dfrac{1}{2}.\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)=\dfrac{1}{2}\left(3^{32}-1\right)=\dfrac{3^{32}}{2}-\dfrac{1}{2}\)

\(\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\dfrac{\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)}{2}\)

\(=\dfrac{3^{32}-1}{2}\)

15 tháng 10 2023

\(4\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\dfrac{1}{2}\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\dfrac{1}{2}\left(3^4-1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\dfrac{1}{2}\left(3^8-1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\dfrac{1}{2}\left(3^{16}-1\right)\cdot\left(3^{16}+1\right)\)

\(=\dfrac{1}{2}\left(3^{32}-1\right)\)

17 tháng 6 2018

trả lời 

tui trả lời rui mà 

chúc bà học tốt

nhớ k tui nha 

cám ơn các bn

27 tháng 5 2019

Ko cái này có +1 nữa

2 tháng 4 2017

 Ta có : A=2005^2005+1/2005^2006+1

=>2005A=2005.(2005^2005+1)/2005^2006+1

=>2005A=2005^2006+2005/2005^2006+1

=>2005A=2005^2006+1+2004/2005^2006+1

=>2005A=2005^2006+1/2005^2006+1 + 1/2005^2006+1

=>2005A=1+1/2005^2006+1

 Lại có:B=2005^2004+1/2005^2005+1

=>2005B=2005.(2005^2004+1)/2005^2005+1

=>2005B=2005^2005+2005/2005^2005+1

=>2005B=2005^2005+1+2004/2005^2005+1

=>2005B=2005^2005+1/2005^2005+1 + 1/2005^2005+1

=>2005B=1+1/2005^2005+1

Vì 2006>2005

=>2005^2006>2005^2005

=>2005^2006+1>2005^2005+1

=>1/2005^2006+1<1/2005^2005+1

=>1+1/2005^2006+1<1+1/2005^2005+1

=>2005A<2005B

=>A<B

Vậy A<B

Ủng hộ mik nha mọi người !!!