Phân tích đa thức thành nhân tử: x^7 + x^5 + 1
Giải thích
x7 + x5 + 1
= (x7 + x6 + x5) – (x6 – 1)
= x5(x2 + x + 1) – (x3 – 1)(x3 + 1)
= x5(x2 + x + 1) – (x – 1)(x2 + x + 1)(x3 + 1)
= (x2 + x + 1)[x5 – (x – 1)(x3 + 1)]
x7 + x5 + 1
= (x7 + x6 + x5) – (x6 – 1)
= x5(x2 + x + 1) – (x3 – 1)(x3 + 1)
= x5(x2 + x + 1) – (x – 1)(x2 + x + 1)(x3 + 1)
= (x2 + x + 1)[x5 – (x – 1)(x3 + 1)]