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Do : b + 1 = a --> a - b = 1
Ta có : ( a + b)( a2 + b2)( a4 + b4)( a8 + b8)( a16 + b16)
= 1.( a + b)( a2 + b2)( a4 + b4)( a8 + b8)( a16 + b16)
= ( a - b)( a + b)( a2 + b2)( a4 + b4)( a8 + b8)( a16 + b16)
= ( a2 - b2)( a2 + b2)( a4 + b4)( a8 + b8)( a16 + b16)
= ( a4 - b4)( a4 + b4)( a8 + b8)( a16 + b16)
= ( a8 - b8)( a8 + b8)( a16 + b16)
= ( a16 - b16)( a16 + b16)
= a32 - b32 ( đpcm)
(a + b)(a2 + b2)(a4 + b4)(a8 + b8)(a16 + b16)
=1.(a + b)(a2 + b2)(a4 + b4)(a8 + b8)(a16 + b16)
= (a – b) (a + b)(a2 + b2)(a4 + b4)(a8 + b8)(a16 + b16)
= (a2 – b2) (a2 + b2)(a4 + b4)(a8 + b8)(a16 + b16)
= (a4 – b4)(a4 + b4)(a8 + b8)(a16 + b16)
= (a8 – b8)(a8 + b8)(a16 + b16)
= (a16– b16)(a16 + b16)
= a32 – b32
Phân tích vế trái ta có:
\(a^{32}-b^{32}=\left(a^{16}\right)^2-\left(b^{16}\right)^2\)
\(=\left(a^{16}+b^{16}\right)\left(a^{16}-b^{16}\right)\)
\(=\left(a^{16}+b^{16}\right)\left(\left(a^8\right)^2-\left(b^8\right)^2\right)\)
\(=\left(a^{16}+b^{16}\right)\left(a^8+b^8\right)\left(a^8-b^8\right)\)
Tượng tự ta có :
\(=\left(a^{16}+b^{16}\right)\left(a^8+b^8\right).....\left(a^4+b^4\right)\left(a^4-b^4\right)\)
\(=\left(a^{16}+b^{16}\right).....\left(a^4+b^4\right)\left(a^2+b^2\right)\left(a^2-b^2\right)\)
\(=\left(a^{16}+b^{16}\right).......\left(a^2+b^2\right)\left(a+b\right)\left(a-b\right)\)
Do a-b=1 nên
\(=>a^{32}-b^{32}=\left(a^{16}+b^{16}\right)....\left(a^4+b^4\right)\left(a^2+b^2\right)\left(a+b\right)\)
CHÚC BẠN HK TỐT............
b) \(B=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(=\left(2-1\right)\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(=\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(=\left(2^{16}-1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(=\left(2^{32}-1\right)\left(2^{32}+1\right)-2^{64}\)
\(=\left(2^{64}-1\right)-2^{64}\)
\(=-1\)
\(\left(1^2-2^2\right)+\left(3^2-4^2\right)+....+\left(99^2-100^2\right)\)
\(=\left(1-2\right)\left(2+1\right)+\left(3-4\right)\left(4+3\right)+....+\left(99-100\right)\left(100+99\right)\)
\(=\left(-1\right)\left(1+2+3+....+100\right)=\frac{\left(-1\right)100.99}{2}=-4950\)
A = 12 – 22 + 32 – 42 + … – 20042 + 20052
A = 1 + (32 – 22) + (52 – 42)+ …+ ( 20052 – 20042)
A = 1 + (3 + 2)(3 – 2) + (5 + 4 )(5 – 4) + … + (2005 + 2004)(2005 – 2004)
A = 1 + 2 + 3 + 4 + 5 + … + 2004 + 2005
A = ( 1 + 2002 ). 2005 : 2 = 2011015
b/ B = (2 + 1)(22 +1)(24 + 1)(28 + 1)(216 + 1)(232 + 1) – 264
B = (22 - 1) (22 +1)(24 + 1)(28 + 1)(216 + 1)(232 + 1) – 264
B = ( 24 – 1)(24 + 1)(28 + 1)(216 + 1)(232 + 1) – 264
B = …
B =(232 - 1)(232 + 1) – 264
B = 264 – 1 – 264
B = - 1
xin lỗi nha chỗ câu a mình lộn
chỗ (1+2002)x2005:2=2011015 là sai nha
(1+2005)x2005:2= 2011015 là đúng nha
tách ít ít ra thôi. để cả cộp thế này k ai làm cho đâu. mệt quá