Cho ba đa thức A = 4x^4 – 2 + 5x^2 – x Tính A + B – C.
Giải thích
A + B – C = (4x4 + 5x2 – x – 2) + (– 3x3 – 4x2 + 5x + 3) – (4x4 – 4x3 + x2 + 4x)
= 4x4 + 5x2 – x – 2 – 3x3 – 4x2 + 5x + 3 – 4x4 + 4x3 – x2 – 4x
= (4x4 – 4x4) + (– 3x3 + 4x3) + (5x2 – 4x2 – x2) + (– x + 5x – 4x) + (– 2 + 3)
= x3 + 1.