a)\(\left(x-y\right)\left(x^3+x^2y+xy^2+y^3\right)=x^4+x^3y+x^2y^2+xy^3-x^3y-x^2y^2-xy^3-y^4=x^4-y^4\)

b) \(x\left(3x-18\right)-3\left(x-4\right)\left(x-2\right)+8=3x^2-18x-3x^2+18x-24+8=-16\)

a, `(8x^3-4x^2): 4x -(4x^2-5x) : 2x + (2x)^2`

`=4x (2x^2-x) : 4x - 2x(2x-5/2 ) :2x + 4x^2`

`=2x^2-x-2x+5/2+4x^2`

`=6x^2-3x+5/2`

b, `(3x^3-x^2y) :x^2 -(xy^2+x^2y) :xy + 2x(x+1)`

`=x^2 (3x-y) :x^2 -xy(y+x) + (2x^2+2x)`

`=3x-y-y-x+2x^2+2x`

`=2x^2+4x-2y`

a: \(=15x^3-6x^2-3x\)

e: \(=x^2-12x+35\)

a/ 5x²y (x²y– 4xy² + 7xy)

`=5x^4y^2-20x^3y^3+35x^3y^2`

b/ 3xy² (x²y³ + x 2y – xy² )

`=3x^3y^5+3x^3y^3-3x^2y^4`

c/ 3x(12x² + 4x – 5) + 2x(9x² – 6x + 7)

`=36x^3+12x^2-15x+18x^3-18x^2+14x`

`=54x^3-6x^2-x`

d/ 5x(2x² – 9x – 5) – 9x (x² - 7x – 4)

`=10x^3-45x^2-25x-9x^3+63x^2+36x`

`=x^3+18x^2+11x`

a: \(A=3\cdot\dfrac{1}{8}\cdot\dfrac{-1}{3}+6\cdot\dfrac{1}{8}\cdot\dfrac{1}{9}+3\cdot\dfrac{1}{2}\cdot\dfrac{-1}{27}\)

\(=-\dfrac{1}{8}+\dfrac{1}{12}-\dfrac{1}{18}\)

\(=-\dfrac{7}{72}\)

b: \(B=\left(-1\cdot3\right)^2+\left(-1\right)\cdot3+\left(-1\right)^3+3^3\)

\(=9-3-1+27=36-4=32\)

c: \(C=-\dfrac{3}{4}xy^2-2x^2y-\dfrac{9}{2}xy\)

\(=\dfrac{-3}{4}\cdot\dfrac{1}{2}\cdot\left(-1\right)^2-2\cdot\dfrac{1}{4}\cdot\left(-1\right)-\dfrac{9}{2}\cdot\dfrac{1}{2}\cdot\left(-1\right)\)

\(=\dfrac{-3}{8}+\dfrac{1}{2}+\dfrac{9}{4}=\dfrac{19}{8}\)

\(a,=3x^3y^3-3x^2y^3+3x^2y^4+3xy^5\\ b,=\left(2x^3-6x^2+10x-3x^2+9x-15\right):\left(x^2-3x+5\right)\\ =\left[2x\left(x^2-3x+5\right)-3\left(x^2-3x+5\right)\right]:\left(x^2-3x+5\right)\\ =2x-3\\ c,=\left[x^2\left(x-3\right)+\left(x-3\right)\right]:\left(x-3\right)=x^2+1\)

mn giúp e ik mn

\(a\text{)}x^2y+xy^2=xy\left(x+y\right)\)

\(b\text{)}x^2-2x+1=\left(x-1\right)^2\)

\(c\text{)}x^2-5x+4=\left(x-1\right)\left(x-4\right)\)

Bài 1: 

a: \(=6x^3-10x^2\)

b: \(=6x+5\)

\(b,=3xy\left(xy+2xy^2-4\right):3xy\\ =xy+2xy^2-4\\ c,=\left[\left(2x^3-x^2+x\right)+\left(6x^2-3x+3\right)\right]:\left(2x^2-x+1\right)\\ =\left[x\left(2x^2-x+1\right)+3\left(2x^2-x+1\right)\right]:\left(2x^2-x+1\right)\\ =\left[\left(x+3\right)\left(2x^2-x+1\right)\right]:\left(2x^2-x+1\right)\\ =x+3\)

b: \(=xy+2xy^2-4\)

Sửa đề: \(A=x^3+x^2y-xy^2-y^3+x^2-y^2+2x+2y+3\)

\(A=x^2\left(x+y\right)-y^2\left(x+y\right)+\left(x-y\right)\left(x+y\right)+2x+2y+3\)

\(=-x^2+y^2+\left(-x+y\right)-2+3\)

\(=-\left(x-y\right)\left(x+y\right)-\left(x-y\right)+1\)

\(=\left(x-y\right)\left(-x-y-1\right)+1\)

\(=\left(x-y\right)\left(1-1\right)+1=1\)