Phân tích đa thức thành nhân tử: x^4 – 25x^2 + 20x – 4.
Giải thích
x4 – 25x2 + 20x – 4
= x4 – 5x3 + 2x2 + 5x3 – 25x2 + 10x – 2x2 + 10x – 4
= x2(x2 – 5x + 2) + 5x(x2 – 5x + 2) – 2(x2 – 5x + 2)
= (x2 – 5x + 2)(x2 + 5x – 2).
x4 – 25x2 + 20x – 4
= x4 – 5x3 + 2x2 + 5x3 – 25x2 + 10x – 2x2 + 10x – 4
= x2(x2 – 5x + 2) + 5x(x2 – 5x + 2) – 2(x2 – 5x + 2)
= (x2 – 5x + 2)(x2 + 5x – 2).