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

Ta có:

A(x) = 4x⁴ – 7x³ + 6x² – 5x – 6.

B(x) = – 4x⁴ + 7x³ –5x²  + 5x + 4

M(x) = A(x) + B(x)

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

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

= x² – 2