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21 tháng 7 2018

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

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

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

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

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

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

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

\(=\dfrac{1}{2}\left(3^{64}-1\right)\)

\(=\dfrac{3^{64}-1}{2}\)

b) \(\left(a+b+c\right)2+\left(a-b-c\right)2+\left(b-c-a\right)2+\left(c-a-b\right)2\)

\(=2\left[\left(a+b+c\right)+\left(a-b-c\right)+\left(b-c-a\right)+\left(c-a-b\right)\right]\)

\(=2\left(a+b+c+a-b-c+b-c-a+c-a-b\right)\)

\(=2.0\)

\(=0\)

c)\(\left(a+b+c+d\right)2+\left(a+b-c-d\right)2+\left(a+c-b-d\right)2+\left(a+d-b-c\right)2\)

\(=2\left(a+b+c+d+a+b-c-d+a+c-b-d+a+d-b-c\right)\)

\(=2.4a\)

\(=8a\)

8 tháng 7 2018

a) Đặt \(A=\left(3+1\right)\left(3^2+1\right)...\left(3^{16}+1\right)\left(3^{32}+1\right)\)

\(2A=2.\left(3+1\right)\left(3^2+1\right)...\left(3^{16}+1\right)\left(3^{32}+1\right)\)

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

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

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

\(...\)

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

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

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

a) \(A=\left(3x+1\right)^2-2\left(3x+1\right)\left(3x+5\right)+\left(5x+5\right)^2\)

\(A=\left[\left(3x+1\right)-\left(5x+5\right)\right]^2\)

\(A=\left(-2x-4\right)^2\)

30 tháng 9 2017

A = (3x + 1)2 - 2(3x + 1)(5x + 5) + (5x + 5)2

= [(3x + 1)-(5x + 5)]2

= (3x + 1 - 5x - 5)2

= [(-2x) - 4]2

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

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

=>2B = (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

vì 2B = 364 - 1

=> B = \(\dfrac{3^{64}-1}{2}\)

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

= 2a2 + 2b2 + 2c2 - 4bc - 2b2 + 4bc - 2c2

= 2a2