Bài 9: Phân tích đa thức thành nhân tử bằng cách phối hợp nhiều phương pháp

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Phong
10 tháng 9 2023 lúc 14:31

a) \(C=\left(5-1\right)\left(5+1\right)\left(5^2+1\right)\left(5^4+1\right)...\left(5^{16}+1\right)\)

\(C=\left(5^2-1\right)\left(5^2+1\right)\left(5^4+1\right)...\left(5^{16}+1\right)\)

\(C=\left(5^4-1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\)

\(C=\left(5^8-1\right)\left(5^8+1\right)\left(5^{16}+1\right)\)

\(C=\left(5^{16}-1\right)\left(5^{16}+1\right)\)

\(C=5^{32}-1\)

b) \(D=15\cdot\left(4^2+1\right)\left(4^4+1\right)...\left(4^{64}+1\right)\)

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

\(D=\left(4^4-1\right)\left(4^4+1\right)\left(4^8+1\right)...\left(4^{64}+1\right)\)

.....

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

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

\(D=4^{128}-1\)

c) \(E=24\left(5^2+1\right)\left(5^4+1\right)...\left(5^{256}+1\right)\)

\(E=\left(5^2-1\right)\left(5^2+1\right)\left(5^4+1\right)...\left(5^{256}+1\right)\)

\(E=\left(5^4-1\right)\left(5^4+1\right)\left(5^8+1\right)...\left(5^{256}+1\right)\)

.....

\(E=\left(5^{128}-1\right)\left(5^{128}+1\right)\left(5^{256}+1\right)\)

\(E=\left(5^{256}-1\right)\left(5^{256}+1\right)\)

\(E=5^{512}-1\)

Nguyễn Lê Phước Thịnh
10 tháng 9 2023 lúc 14:32

a: \(C=\left(5^2-1\right)\left(5^2+1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\)

\(=\left(5^4-1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\)

\(=\left(5^8-1\right)\left(5^8+1\right)\left(5^{16}+1\right)\)

\(=\left(5^{16}-1\right)\left(5^{16}+1\right)=5^{32}-1\)

b: \(D=\left(4^2-1\right)\left(4^2+1\right)\left(4^4+1\right)\cdot...\cdot\left(4^{64}+1\right)\)

\(=\left(4^4-1\right)\left(4^4+1\right)\left(4^8+1\right)\left(4^{16}+1\right)\left(4^{32}+1\right)\left(4^{64}+1\right)\)

\(=\left(4^8-1\right)\left(4^8+1\right)\left(4^{16}+1\right)\left(4^{32}+1\right)\left(4^{64}+1\right)\)

\(=\left(4^{16}-1\right)\left(4^{16}+1\right)\left(4^{32}+1\right)\left(4^{64}+1\right)\)

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

\(=\left(4^{64}-1\right)\left(4^{64}+1\right)=4^{128}-1\)

c: \(E=\left(5^2-1\right)\left(5^2+1\right)\cdot...\cdot\left(5^{128}+1\right)+5^{256}-1\)

\(=\left(5^4-1\right)\left(5^4+1\right)\left(5^8+1\right)\cdot...\cdot\left(5^{128}+1\right)+5^{256}-1\)

\(=\left(5^8-1\right)\left(5^8+1\right)\cdot...\cdot\left(5^{128}+1\right)+5^{256}-1\)

\(=\left(5^{16}-1\right)\left(5^{16}+1\right)\left(5^{32}+1\right)\left(5^{64}+1\right)\left(5^{128}+1\right)+5^{256}-1\)

\(=\left(5^{32}-1\right)\left(5^{32}+1\right)\left(5^{64}+1\right)\left(5^{128}+1\right)+5^{256}-1\)

\(=\left(5^{64}-1\right)\left(5^{64}+1\right)\left(5^{128}+1\right)+5^{256}-1\)

\(=5^{256}-1+5^{256}-1=2\cdot5^{256}-2\)

Kiều Vũ Linh
10 tháng 9 2023 lúc 14:40

a) C = (5 - 1)(5 + 1)(5² + 1)(5⁴ + 1)...(5¹⁶ + 1)

= (5² - 1)(5² + 1)(5⁴ + 1)...(5¹⁶ + 1)

= (5⁴ - 1)(5⁴ + 1)...(5¹⁶ + 1)

= (5⁸ - 1)...(5¹⁶ + 1)

= 5³² - 1

b) D = 15(4² + 1)(4⁴ + 1)...(4⁶⁴ + 1)

= (4² - 1)(4² + 1)(4⁴ + 1)...(4⁶⁴ + 1)

= (4⁴ - 1)(4⁴ + 1)...(4⁴⁶ + 1)

= (4¹⁶ - 1)...(4⁶⁴ + 1)

= 4¹²⁸ - 1

c) E = 24(5² + 1)(5⁴ + 1)...(5¹²⁸ + 1)(5²⁵⁶ + 1)

= (5² - 1)(5² + 1)(5⁴ + 1)...(5¹²⁸ + 1)(5²⁵⁶ + 1)

= (5⁴ - 1)(5⁴ + 1)...(5¹²⁸ + 1)(5²⁵⁶ + 1)

= (5⁸ - 1)...(5¹²⁸ + 1)(5²⁵⁶ + 1)

= (5²⁵⁶ - 1)(5²⁵⁶ + 1)

= 5⁵¹² - 1


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