Question

[PU PU]

Thực hiện phép tính

a,\(\left(x-y\right)\left(y^2+y+1\right)+\left(\dfrac{1}{3}x^2y-y\right)\left(2x+y^2\right)\)

b,\(2x^2\left(x-2\right)+3x\left(x^2-x-2\right)-5\left(3-x^2\right)\)

c,\(\left(x-1\right)\left(x-3\right)-\left(4-x\right)\left(2x-1\right)-3x^3+2x-5\)

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(=xy^2+xy+x-y^3-y^2-y+\dfrac{2}{3}x^3y+\dfrac{1}{3}x^2y^3-2xy-y^3\)

\(=xy^2-xy+x-2y^3-y^2-y+\dfrac{2}{3}x^3y+\dfrac{1}{3}x^2y^3\)

b: \(=2x^3-4x^2+3x^3-3x^2-6x-15+5x^2\)

\(=5x^3-2x^2-6x-15\)

c: \(=x^2-4x+3+\left(x-4\right)\left(2x-1\right)-3x^3+2x-5\)

\(=-3x^3+x^2-2x-2+2x^2-x-8x+4\)

\(=-3x^3+3x^2-11x+2\)