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29 tháng 7 2017

a, \(A=1999.2001=\left(2000-1\right)\left(2000+1\right)=2000^2-1< 2000^2=B\)

Vậy A<B

b, \(A=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)

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

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

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

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

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

Vậy A<B

29 tháng 7 2017

a, \(A=1999.2001=\left(2000-1\right)\left(2000+1\right)\)

\(=2000^2-1< 2000^2\)

\(\Rightarrow A< B\)

b, \(A=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)

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

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

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

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

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

\(=2^{32}-1< 2^{32}\)

\(\Rightarrow A< B\)

12 tháng 8 2016

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

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

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

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

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

\(=\left(2^{16}-1\right)\left(2^{16}+1\right)=2^{32}-1\)

\(B=2^{32}\)

=> \(A< B\)

12 tháng 8 2016

ta có A= \(\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)

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

=\(2^{32}-1\)    (ấp dụng các hằng đẳng thức )

=> A=232-1

B=232

=> A<B

7 tháng 7 2018

a) Ta có: \(A=1999.2001=\left(2000-1\right)\left(2000+1\right)=2000^2-1< 2000^2\)

Vậy A < 20002

c) \(E=26^2-24^2=\left(26-24\right)\left(26+24\right)=2.50\)

    \(F=27^2-25^2=\left(27-25\right)\left(27+25\right)=2.52\)

Vì 50 < 52 => 2.50 < 2.52

=> E < F

18 tháng 10 2015

Phân tích 3=4-1=\(2^2-1\)

4 tháng 7 2017

Ta có:

a) A = 2018 x 2020 = (2019 - 1) x (2019 + 1)

Áp dụng hằng đẳng thức thứ ba ta có:

A = 208 x 2020 = \(2019^2-1^2=2019^2-1\)

\(2019^2-1< 2019^2\)

\(\Rightarrow\)A < B

b) A = \(\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)

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

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

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

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

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

\(2^{32}-1< 2^{32}\)

\(\Rightarrow\)A < B

4 tháng 7 2017

a) Áp dụng hàng đăng thức (a - b) (a + b) = a2 - b2

Ta có : A = 2018.2020 = (2019 - 1) (2019 + 1) = 20192 - 1

Mà B =  20192 

Nên A < B 

6 tháng 7 2016

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

mà B= \(2^{32}\)

=> A<B

6 tháng 7 2016

giải thích rõ hơn được k bạn

A=(2+1)x(22+1)x(24+1)x(28+1)x(216+1)

= 3.5.17.257.65537

   = 42949672995 = 232
 
⇒A = B
mình nhé 
10 tháng 8 2019

B=\(2^{16}-1\)

\(A=2+1.2^2+1.2^4+1.2^8+1\)\(=\left(2.2^2.2^4.2^8\right)+\left(1+1+1+1\right)\)\(=2^{15}+4\)

mà \(2^{16}>2^{15}\)=> A>B

10 tháng 8 2019

à nhầm B>A

12 tháng 7 2018

a, \(A=1999.2001=\left(2000-1\right)\left(2000+1\right)=2000^2-1< 2000^2=B\)

Vậy A<B

b, \(B=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)=\left(2-1\right)\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\)

\(=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\)

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

Vậy A>B