Cho hai đa thức:P(x) = 5x^3 + x^2 – x + 3; Q(x) = x^3 – 2x^2 + 3x + 2.Tính P(x) + Q(x); P(x) – Q(x).
Giải thích
P(x) + Q(x) = (5x3 + x2 – x + 3) + (x3 – 2x2 + 3x + 2)
= 5x3 + x2 – x + 3 + x3 – 2x2 + 3x + 2
= 6x3 – x2 + 2x + 5
P(x) – Q(x) = (5x3 + x2 – x + 3) – (x3 – 2x2 + 3x + 2)
= 5x3 + x2 – x + 3 – x3 + 2x2 – 3x – 2
= 4x3 + 3x2 – 4x + 1