Phân tích đa thức thành nhân tử x4 – 2x3 + 2x – 1.
Giải thích
x4 – 2x3 + 2x – 1
= x4 – x3 – x3 + x2 – x2 + x + x – 1
= x3(x – 1) – x2(x – 1) – x(x – 1) + (x – 1)
= (x – 1)(x3 – x2 – x + 1)
= (x – 1)[x2(x – 1) – (x – 1)]
= (x – 1)(x – 1)(x2 – 1)
= (x – 1)3(x + 1).