\(2x^2y+4xy^2+2y^3-8\) 

\(=2y\left(x^2+2xy+y^2\right)-8\)

\(=2y\left(x+y\right)^2-8\) 

\(=2\left[y\left(x+y\right)^2-4\right]\)

thank you huỳnh thanh phong

1.A

2.C

3.B

4.C

a

c

b

c

(x-1)y^2-4(x-1)y

b) \(x^3-4x^2y+4xy^2-y^3\)

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

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

\(=\left(x-y\right)^3-xy\left(x-y\right)\)

\(=\left(x-y\right)\left[\left(x-y\right)^2-xy\right]\)

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

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

x² - 2x + 2y - xy = (x² - 2x) - (xy - 2y) = x(x - 2) - y(x - 2) = (x - 2)(x - y)

x² + 4xy - 16 + 4y² = (x² + 4xy + 4y²) - 16 = (x + 2y)² - 16 = (x + 2y + 4)(x + 2y - 4)

cảm ơn nha

\(R=\left(2x\right)^2-2.2x.y+y^2\\ =\left(2x-y\right)^2\\ =>D\)

Bài làm:

1) Ta có: \(2x^2+5xy+2y^2\)

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

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

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

2) Ta có: \(2x^2+2xy-4y^2\)

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

\(=2x\left(x-y\right)+4y\left(x-y\right)\)

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

\(1)2x^2+5xy+2y^2=2x^2+4xy+xy+2y^2=\left(2x^2+4xy\right)+\left(xy+2y^2\right)=2x\left(x+2y\right)+y\left(x+2y\right)=\left(2x+y\right)\left(x+2y\right)\)\(2)2x^2+2xy-4y^2=2x^2+4xy-2xy-4y^2=\left(2x^2-2xy\right)+\left(4xy-4y^2\right)=2x\left(x-y\right)+4y\left(x-y\right)=\left(2x+4y\right)\left(x-y\right)\)

a,\(2x^2+5xy+2y^2\)

\(=2x^2+4xy+xy+2y^2\)

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

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

b,\(2x^2+2xy-4y^2\)

\(=2x^2-2xy+4xy-4y^2\)

\(=2x\left(x-y\right)+4y\left(x-y\right)\)

\(=\left(x-y\right)\left(2x+4y\right)\)

\(=4xy\left(1-5x^2y+4xy\right)\)

=4xy(1-  5x²y+4xy) 

= 4xy ( 1 - 20x²y + 4xy )

a, x²-7x-14y+2x

=x(x+2)-7(x-2y)

b, x³-4x²y+4xy²-25x

=x³-4x²y+4xy²-y³-25x+y³

=(x-y)³-25x+y³

a ) = x(x+2) - 7(x+2y)

b) =  -4 xy ( x-y) + (x^3-25x)  [ câu này mk , chaqcs là làm đúng đâu ]