Đáp án:
Giải thích các bước giải:
d,đặt S=(3+1)(3^2+1)(3^4+1)(3^8+1)(3^16+1)(3^32+1)`
`2S=(3-1)(3+1)(3^2+1)(3^4+1)(3^8+1)(3^16+1)(3^32+1)`
`2S=(3^2-1)(3^2+1)(3^4+1)(3^8+1)(3^16+1)(3^32+1)`
`2S=(3^4-1)(3^4+1)(3^8+1)(3^16+1)(3^32+1)`
`2S=(3^8-1)(3^8+1)(3^16+1)(3^32+1)`
`2S=(3^16-1)(3^16+1)(3^32+1)`
`2S=(3^32-1)(3^32+1)`
`2S=3^64-1`
`=>S=(3^64-1)/2`
e,`(a+b-c)^2+(a-b+c)^2-2(b-c)^2`
`=a^2+b^2+c^2+2ab-2bc-2ac+a^2+b^2+c^2-2ab-2bc+2ac-2(b^2-2bc+b^2)`
`=2a^2`
