Tìm đa thức C(x) sao cho A(x) = B(x) + C(x)

A(x) = B(x) + C(x) ⇒C(x) = A(x) – B(x)

= (4x⁴ – 7x³ + 6x² – 5x – 6) – (– 4x⁴ + 7x³ – 5x²  + 5x + 4)

= 4x⁴ – 7x³ + 6x² – 5x – 6 + 4x⁴ – 7x³ + 5x²  – 5x – 4

= 4x⁴ + 4x⁴ – 7x³ – 7x³ + 6x² + 5x²  – 5x – 5x – 6 – 4

= 8x⁴ – 14x³ + 11x² – 10x – 10