\(A=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^4+1\right)+...">
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14 tháng 7 2016

a) (2+1)(2^2+1)(2^4+1)...(2^32+1)-2^64

=(2+1)(2-1)(2^2+1)(2^4+1)...(2^32+1)-2^64

=(2^2-1)(2^2+1)(2^4+1)...(2^32+1)-2^64

=(2^4-1)(2^4+1)....(2^32+1)-2^64

=......

=(2^32-1)(2^32+1)-2^64

=2^64-1-2^64=-1

b)Đặt A=(5+3)(5^2+3^2)(5^4+3^4)...(5^64+3^64)+(5^128-3^128)/2

đặt B=(5+3)(5^2+3^2)(5^4+3^4)...(5^64+3^64)

\(2B=\left(5-3\right)\left(5+3\right)\left(5^2+3^2\right)\left(5^4+3^4\right)...\left(5^{64}+3^{64}\right)\)

\(2B=\left(5^2-3^2\right)\left(5^2+3^2\right)\left(5^4+3^4\right)...\left(5^{64}+3^{64}\right)\)

\(2B=\left(5^4-3^4\right)\left(5^4+3^4\right)...\left(5^{64}+3^{64}\right)\)

\(2B=.......\)

2B=(5^64-3^64)(5^64+3^64)

2B=5^128-3^128

B=(5^128-3^128)/2 (thế vào đề bài)

=> A=B+(5^128-3^128)/2=(5^128-3^128)/2+(5^128-3^128)/2=\(\frac{2\left(5^{128}-3^{128}\right)}{2}=\left(5^{128}-3^{128}\right)\)

14 tháng 7 2016

a) A = ( 2-1)(2+1)(22+1)...(232+1)-264

         =(22-1)(22+1)(24+1)... -264

       =....

       =264-1-264=1

câu b tương tự nhá

8 tháng 3 2020

Ta có \(A=\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\cdot\cdot\cdot\left(3^{64}+1\right)\)

\(\Rightarrow2A=\left(3-1\right)\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\cdot\cdot\cdot\left(3^{64}+1\right)\)

\(=\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\cdot\cdot\cdot\left(3^{64}+1\right)\)

\(=\left(3^4-1\right)\left(3^4+1\right)\cdot\cdot\cdot\left(3^{64}+1\right)\)

\(=\left(3^{64}-1\right)\left(3^{64}+1\right)=\left(3^{128}-1\right)\)

\(\Rightarrow A=\frac{3^{128}-1}{2}\)

21 tháng 10 2016

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

= (100 - 99)(100 + 99) + (98 - 97)(98 + 97) + . . . (2 - 1)(2 + 1)

= 199 + 195 + . . . + 3

= 5050

B = 3(22 + 1)(24 + 1) . . . (264 + 1) + 1

= (22 - 1)(22 + 1)(24 + 1)(28 + 1)(216 + 1)(232 + 1)(264 + 1)(264 + 1) + 1

= (24 - 1)(24 + 1)(28 + 1)(216 + 1)(232 + 1)(264 + 1) + 1

= (28 - 1)(28 + 1)(216 + 1)(232 + 1)(264 + 1) + 1

= (216 - 1)(216 + 1)(232 + 1)(264 + 1) + 1

= (232 - 1)(232 + 1)(264 + 1) + 1

= (264 - 1)(264 + 1) + 1

= 2128 - 1 + 1

= 2128

22 tháng 10 2016

Câu C mk chép nhầm đề đó

5 tháng 11 2017

a, \(A=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)...\left(2^{32}+1\right)-2^{64}\)

\(=\left(2-1\right)\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)...\left(2^{32}+1\right)-2^{64}\)

\(=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)...\left(2^{32}+1\right)-2^{64}\)

\(=\left(2^{32}-1\right)\left(2^{32}+1\right)-2^{64}=2^{64}-1-2^{64}=-1\)

b,\(B=\left(5+3\right)\left(5^2+3^2\right)\left(5^4+3^4\right)...\left(5^{64}+3^{64}\right)+\dfrac{5^{128}-3^{128}}{2}\)

\(=\dfrac{\left(5-3\right)\left(5+3\right)\left(5^2+3^2\right)\left(5^4+3^4\right)...\left(5^{64}+3^{64}\right)}{2}+\dfrac{5^{128}-3^{128}}{2}\)\(=\dfrac{\left(5^2-3^2\right)\left(5^2+3^2\right)\left(5^4+3^4\right)...\left(5^{64}+3^{64}\right)+5^{128}-3^{128}}{2}\)

\(=\dfrac{\left(5^{64}-3^{64}\right)\left(5^{64}+3^{64}\right)+5^{128}-3^{128}}{2}=\dfrac{2.5^{128}}{2}=5^{128}\)

18 tháng 8 2016

a) ( x2 - 2x + 2 )( x- 2 )( x2 + 2x + 2 )( x2 + 2 )

= [ ( x+ 2 )2 - 4x2 ] ( x4 - 4 )

= ( x4 + 4 ) ( x4 - 4 )

= x8 - 16

b) ( a + b + c )2 + ( a + b - c )2 + ( 2a -b )2

= 2 ( a2 + b2 + c2 ) + 2 ( ab + bc + ac ) + 2 ( ab - bc - ac ) + ( 4a2 - 4ab + b2 )

= 2 ( a+ b2 + c2 ) + 4ab - 4ab + 4a2 + b2

= 6a2 + 3b2 + 2c2

c) 1002 - 992 + 982 - 972 + ..... + 22 - 12

= ( 100 - 99 )( 100 + 99 ) + ( 98 - 97 )( 98 + 97 ) + ..... + ( 2 - 1 )( 2 + 1 )

= 199 + 197 + 195 + ..... + 5 + 3

\(\frac{\left(199+3\right)\left(\left(199-3\right)\frac{1}{2}+1\right)}{2}\)

= 9999

d) 3 ( 22 + 1 )( 24 +1 )......( 264 + 1 ) + 1

= ( 22 -1 )( 22 + 1 )(24 + 1 ).....( 264 + 1 ) + 1

= ( 24 -1 )( 24 + 1 )( 28 + 1 )......( 264 + 1 ) +1

= ( 28 -1 )( 28 + 1).....( 264 + 1) +1

............

= ( 264 - 1)( 264 +1 ) + 1

= 2128

17 tháng 8 2020

a) \(5x^2-2x\left(3x+\frac{3}{2}\right)=-x^2-3x=-x\left(x+3\right)=-3\left(3+3\right)=-18\)

b) \(3x\left(x-4y\right)-\frac{12}{5}y\left(y-5x\right)=3x^2-\frac{12}{5}y^2=3\left(x^2-\frac{4}{5}y^2\right)\)

\(=3\left(4^2-\frac{4}{5}.5^2\right)=3.\left(-4\right)=-12\)

c) \(\left(x-2\right)^2-\left(x+7\right)\left(x-7\right)=x^2-4x+4-x^2+49=-4x+53=-4.3+53=41\)

d) \(x^2+12x+36=\left(x+6\right)^2=\left(64+6\right)^2=70^2=4900\)

e) \(\left(x-3\right)^2-\left(x-4\right)\left(x+4\right)=x^2-6x+9-x^2+16=-6x+25=-6\left(-1\right)+25\)

= 31

f) \(\left(3x+2y\right)^2-4y\left(3x+y\right)=9x^2+12xy+4y^2-12xy-4y^2=9x^2=9\left(-\frac{1}{3}\right)^2=1\)

17 tháng 8 2020

a, \(5x^2-2x\left(3x+\frac{3}{2}\right)=-x^2-3x\)

Thay x = 3 vào biểu thức trên ta cs : \(-3^2-3.3=-9-9=-18\)

b, \(3x\left(x-4y\right)-\frac{12}{5}y\left(y-5x\right)=3x^2-\frac{12}{5}y^2\)

Thay x = 4 ; y = 5 vào biểu thức trên ta có : \(3.4^2-\frac{12}{5}.5^2=-12\)