so sanh a va b: A= (3+1)(3`2+1)(3`4+1)(3`8+1)(3`16+1) B=3`32-1

Giải thích các bước giải:

A=(3 + 1)(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^16 + 1) 2A=2(3 + 1)(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^16 + 1) 2A=(3-1)(3 + 1)(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^16 + 1) 2A=(3^2-1)(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^16 + 1) 2A=(3^4-1)(3^4 + 1)(3^8 + 1)(3^16 + 1) 2A=(3^8-1)(3^8 + 1)(3^16 + 1) 2A=(3^16-1)(3^16 + 1) 2A=3^32 - 1 = B => A<B

ok nhé

Ta có:

` A=(3 + 1)(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^{16} + 1) `

` <=> 2A=2(3 + 1)(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^{16} + 1) `

` <=> 2A=(3-1)(3 + 1)(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^{16} + 1) `

` <=> 2A=(3^2-1)(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^{16} + 1) `

` <=> 2A=(3^4-1)(3^4 + 1)(3^8 + 1)(3^{16} + 1) `

` <=> 2A=(3^8-1)(3^8 + 1)(3^{16} + 1) `

` <=> 2A=(3^{16}-1)(3^{16}+ 1) `

` <=> 2A=3^{32} - 1 `

Mà ` B = 3^{32} - 1 `

` => 2A = B `

` => A<B `