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

b, \(3\left(x-y\right)-5x\left(y-x\right)=\left(3+5x\right)\left(x-y\right)\)

c, \(\dfrac{2}{5}x\left(y-1\right)+\dfrac{2}{5}y\left(1-y\right)=\left(\dfrac{2}{5}x-\dfrac{2}{5}y\right)\left(y-1\right)=\dfrac{2}{5}\left(x-y\right)\left(y-1\right)\)

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

a) = (x - 1)(5x - 3)

b) = x(x + y) - 5(x + y)

= (x + y)(x - 5)

c) = x(x - y) - y(x - y)

= (x - y)^2

d) = 2(x² + 2x + 1 - y²)

= 2[(x + 1)² - y²]

= 2(x - y + 1)(x + y + 1)

a)Ta có:  \(x\left(x-y\right)+5x-5y=x\left(x-y\right)+\left(5x-5y\right)\)

\(=x\left(x-y\right)+5\left(x-y\right)=\left(x-y\right)\left(x+5\right)\)

b) \(x^2-y^2+10x+25=\left(x^2+10x+25\right)-y^2=\left(x+5\right)^2-y^2\)

\(=\left(x+5-y\right)\left(x+5+y\right)\)

b ) 5 x ( x - 1 ) - 3x ( x - 1 )

= ( 5x - 3x ) ( x - 1 )

= 2x ( x - 1 )

c ) x ( x + y ) - 5 x - 5y

= x ( x + y ) - 5 ( x + y )

= ( x - 5 ) (x + y )

d ) x ^ 2 + xy + x

= x ( x + y + 1 )

e ) x ( x - y ) + y ( y - x )

= x ( x - y ) - y ( x - y )

= ( x - y ) ( x -y )

= ( x - y ) ²

a, 5x(x-1)-3x(x-1)=(5x-3x)(x-1)=2x(x-1)

b, x(x+y)-5x-5y=x(x+y)-5(x+y)=(x-5)(x+y)

c, x²+xy+x=x(x+y+1)

d, x(x-y)+y(y-x)=x(x-y)-y(x-y)=(x-y)(x-y)=(x-y)²

b)5x(x-1)-3x(x-1)=x(x-1).(5-3)=x(x-1).2

c)x(x+y)-5x-5y=x(x+y)-(5x+5y)=x(x+y)-[5(x+y)[=(x+y).(x-5)

d)x^2+xy+x=x(x+y+1)

e)x(x-y)+y(y-x)=x(x-y)-(x-y).y=(x-y).(x-y)

a: =x^2(x^2+2x+1)

=x^2(x+1)^2

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

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

=(x+y)[(x+y)^2-1]

=(x+y)(x+y-1)(x+y+1)

c: =5(x^2-2xy+y^2-4z^2)

=5(x-y-2z)(x-y+2z)

14.C

15.D

Câu 14: C

Câu 15: D

14:A
15:D

\(=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)=\left(x-y\right)\left(x+y-5\right)\)

\(=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)=\left(x+y-5\right)\left(x-y\right)\)

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