`B= (x+1)(x^7-x^6+x^5-x^4+x^3-x^2+x-1)`

Đáp án:+Giải thích các bước giải:

`B = ( x + 1 ) ( x ^7 − x ^6 + x^ 5 − x^ 4 + x ^3 − x ^2 + x − 1 )`

`= ( x + 1 ) [ x^6 ( x − 1 ) + x^4 ( x − 1 ) + x^2 ( x − 1 ) + ( x − 1 ) ]`

`= ( x + 1 ) ( x ^6 + x^ 4 + x ^2 + 1 )`

`= ( x + 1 ) ( x + 1 ) ( x ^4 + 1 )`