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15 tháng 9 2019

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

\(\Leftrightarrow2A=\left(3-1\right)\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(\Leftrightarrow2A=\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(\Leftrightarrow2A=\left(3^4-1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(\Leftrightarrow2A=\left(3^8-1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(\Leftrightarrow2A=\left(3^{16}-1\right)\left(3^{16}+1\right)\)

\(\Leftrightarrow2A=3^{32}-1\)

\(\Leftrightarrow A=3^{31}-\frac{1}{2}\)

27 tháng 12 2016

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

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

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

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

\(=\left(3^{32}-1\right)\left(3^{32}+1\right)=3^{64}-1\)

17 tháng 9 2016

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

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

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

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

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

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

7 tháng 7 2015

đặt A=(3+1)(32+1)(34+1)(38+1)(316+1)(332+1)

=>2A=2.(3+1)(32+1)(34+1)(38+1)(316+1)(332+1)

=>2A=(3-1)(3+1)(32+1)(34+1)(38+1)(316+1)(332+1)

=(32-1)(32+1)(34+1)(38+1)(316+1)(332+1)

=(34-1)(34+1)(38+1)(316+1)(332+1)

=(38-1)(38+1)(316+1)(332+1)

=(316-1)(316+1)(332+1)

=(332-1)(332+1)

=364-1

=>2A=\(\frac{3^{64}-1}{2}\)

15 tháng 7 2018

bạn ơi: A=\(\frac{3^{64}-1}{2}\) chứ ko phải 2A=\(\frac{3^{64}-1}{2}\)

a: \(=\dfrac{3^8-3^6+3^6\cdot2^3}{5^3}=\dfrac{3^8-3^6\left(1-2^3\right)}{5^3}=\dfrac{11664}{125}\)

b: \(=\dfrac{7^4\cdot4-7^3}{7^3}=7\cdot4-1=27\)

c: \(=28^4-28^4+1=1\)

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

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

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

\(=3^{32}\)

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

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

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

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

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

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

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

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

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

\(\Rightarrow\) \(B< A\)

14 tháng 7 2015

Câu b đúng r mà trieu dang

13 tháng 7 2015

như thế này chứ:

A=1002-992+982-972+...+22-12

B=12-22+32-42+...-20082-20092

C=3.(22+1)(24+1)(28+1)(216+1)-232

4 tháng 10 2020

Đặt A = ( 3 + 1 )( 32 + 1 )( 34 + 1 )( 38 + 1 )( 316 + 1 )( 332 + 1 )

=> 2A = 2.( 3 + 1 )( 32 + 1 )( 34 + 1 )( 38 + 1 )( 316 + 1 )( 332 + 1 )

          = ( 3 - 1 )( 3 + 1 )( 32 + 1 )( 34 + 1 )( 38 + 1 )( 316 + 1 )( 332 + 1 )

          = ( 32 - 1 )( 32 + 1 )( 34 + 1 )( 38 + 1 )( 316 + 1 )( 332 + 1 )

          = ( 34 - 1 )( 34 + 1 )( 38 + 1 )( 316 + 1 )( 332 + 1 )

          = ( 38 - 1 )( 38 + 1 )( 316 + 1 )( 332 + 1 )

          = ( 316 - 1 )( 316 + 1 )( 332 + 1 )

          = ( 332 - 1 )( 332 + 1 )

          = 364 - 1

2A = 364 - 1 => A = \(\frac{3^{64}-1}{2}\)