Cho hai đa thức: P(x) = 2x^4 + 2x^3 – 3x^2 + x + 6; Q(x) = x^4 – x^3 – x^2 + 2x + 1.Tính P(x) + Q(x); P(x) – Q(x).

P(x) + Q(x) = (2x⁴ + 2x³ – 3x² + x + 6) + (x⁴ – x³ – x² + 2x + 1)

= 2x⁴ + 2x³ – 3x² + x + 6 + x⁴ – x³ – x² + 2x + 1

= 3x⁴ + x³ – 4x² + 3x + 7

P(x) – Q(x) = (2x⁴ + 2x³ – 3x² + x + 6) – (x⁴ – x³ – x² + 2x + 1)

= 2x⁴ + 2x³ – 3x² + x + 6 – x⁴ + x³ + x² – 2x – 1

= x⁴ + 3x³ – 2x² – x + 5