急!!!65點!!!多項式!!

1. (2x^2 - 7pq^2) - (-4q + q^3) + 2q^3
= 2x^2 - 7pq^2 + 4q - q^3 + 2q^3
= 2x^2 - 7pq^2 + 4q + q^3
= q^3 - 7pq^2 + 4q + 2x^2

2.(a) (2x^2 - y)(4y - 5x)
= 2x^2(4y - 5x) - y(4y - 5x)
= 8yx^2 - 10x^3 - 4y^2 + 5xy
= -10x^3 + 8yx^2 + 5xy - 4y^2

2.(b) (3x^2 - x + 1)(x + 2)
= 3x^2(x + 2) - x(x + 2) + 1(x + 2)
= 3x^3 + 6x^2 - x^2 - 2x + x + 2
= 3x^3 + 5x^2 - x + 2

2x^2 即是 2x 的 2 次方