g: (x+3y)(x-3y+2)

=(x+3y)(x-3y)+2(x+3y)

=x^2-9y^2+2x+6y

h: (x+2y)(x-2y+3)

=(x+2y)(x-2y)+3(x+2y)

=x^2-4y^2+3x+6y

i: (x^2-xy+y^2)(x+y)

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

=x^3+y^3

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

k: (5x-2y)(x^2-xy-1)

=5x*x^2-5x*xy-5x-2y*x^2+2y*xy+2y

=5x^3-5x^2y-5x-2x^2y+2xy^2+2y

=5x^3-7x^2y+2xy^2-5x+2y

l: (x^2y^2-xy+y)(x-y)

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

\(xy+14+2y+7x=-10\)

\(\Rightarrow xy+7x+7y=-24\)

\(\Rightarrow x\left(y+7\right)+7y=-24\)

\(\Rightarrow x\left(y+7\right)+7y+49=-24+49\)

\(\Rightarrow x\left(y+7\right)+7\left(y+7\right)=25\)

\(\Rightarrow\left(x+7\right)\left(y+7\right)=25\)

\(\Rightarrow\left(x+7\right);\left(y+7\right)\inƯ\left(25\right)=\left\{\pm1;\pm5;\pm25\right\}\)

Xét bảng 

Vậy.........................

\(xy+x+y=2\)

\(\Rightarrow x\left(y+1\right)+\left(y+1\right)=2+1\)

\(\Rightarrow\left(x+1\right)\left(y+1\right)=3\)

\(\Rightarrow\left(x+1\right);\left(y+1\right)\inƯ\left(3\right)=\left\{\pm1;\pm3\right\}\)

Xét bảng 

Vậy.....................................

\(xy-10+5x-3y=2\)

\(\Rightarrow xy-5x-3y=12\)

\(\Rightarrow x\left(y-5\right)-3y+15=12+15\)

\(\Rightarrow x\left(y-5\right)-3\left(y-5\right)=27\)

\(\Rightarrow\left(x-3\right)\left(y-5\right)=27\)

\(\Rightarrow\left(x-3\right);\left(y-5\right)\inƯ\left(27\right)=\left\{\pm1;\pm3;\pm9;\pm27\right\}\)

Tự xét bảng như trên 

\(xy-1=3x+5y+4\)

\(\Rightarrow xy-3x-5y=4+1\)

\(\Rightarrow x\left(y-3\right)-5y+15=1+4+15\)

\(\Rightarrow x\left(y-3\right)-5\left(y-3\right)=20\)

\(\Rightarrow\left(x-5\right)\left(y-3\right)=20\)

\(\Rightarrow\left(x-5\right)\left(y-3\right)\inƯ\left(20\right)=\left\{\pm1;\pm2;\pm4;\pm5;\pm10;\pm20\right\}\)

Xét bảng 

Vậy......................................

a: =>A-B=3x^2y-4xy^2+x^2y-2xy^2=4x^2y-6xy^2

b: =>B-A=-7xy^2+8x^2y-5xy^2+6x^2y=-12xy^2+14x^2y

=>A-B=12xy^2-14x^2y

c: =>B-A=8x^2y^3-4x^3y-3x^2y^3+5x^3y^2=5x^2y^3+x^3y^2

=>A-B=-5x^2y^3-x^3y^2

d: =>A-B=2x^2y^3-7x^3y+6x^2y^3+3x^3y^2=8x^2y^3-7x^3y+3x^3y^2

ta có 4 x 3 y 2   –   8 x 2 y 3   =   4 x 2 y 2 . x   –   4 x 2 y 2 . 2 y   =   4 x 2 y 2 ( x   –   2 y )    

Vậy 4x³y² – 8x²y³ = 4x²y²(x – 2y)      

Đáp án cần chọn là: C

bấm đúng cho mik đi 

\(\left\{{}\begin{matrix}2xy+x+2y=5\\xy+3x-3y=5\end{matrix}\right.\)

\(\Rightarrow2xy+x+2y=xy+3x-3y\)

\(\Rightarrow2xy+x+2y-xy-3x+3y=0\)

\(\Rightarrow\left(2xy-xy\right)+\left(x-3x\right)+\left(2y+y\right)=0\)

\(\Rightarrow xy-2x+3y=0\)

\(\Rightarrow xy-2x+3y-6=-6\)

\(\Rightarrow x\left(y-2\right)+3\left(y-2\right)=-6\)

\(\Rightarrow\left(x+3\right)\left(y-2\right)=-6\)

Xét ước là xong,mấy câu kia tương tự

bài này của bn giống mk DDT Miner Ter

A - B = (x³y - 2xy + 5xy² - 3x²y² - 1) - (-2x³y - xy² + 2x²y² - xy + 8)

        = x³y - 2xy + 5xy² - 3x²y² - 1 + 2x³y + xy² - 2x²y² + xy - 8

        = (x³y + 2x³y) + (-2xy + xy) + (5xy² + xy²) + (-3x²y² - 2x²y²) + (-1 - 8)

        = 3x³y  - xy + 6xy² - 5x²y² - 9

a-b=(x^3y-2xy+5xy^2-3x^2y^2-1)-(-2x^3y-xy^2+2x^2y^2-xy+8)

        =x^3y-2xy+5xy^2-3x^2y^2-1+2x^3y+xy^2-2x^2y^2+xy-8

       =x^3y+(-2xy+xy)+(5xy^2+xy^2)+(-3x^2y^2-2x^2y^2)+(-1-8)

       =x^3y-1xy+6xy^2-5x^2y^2-9