a) 4x² - 5xy + y² = 4x² - 4xy - xy + y² = 4x( x - y ) - y( x - y ) = ( x - y )( 4x - y )

b) x² - 4xy + 3y² = x² - xy - 3xy + 3y² = x( x - y ) - 3y( x - y ) = ( x - y )( x - 3y )

c) 9x² + 6xy - 8y² = 9x² - 6xy + 12xy - 8y² = 9x( x - 2/3y ) + 12y( x - 2/3y ) = ( x - 2/3y )( 9x + 12y )

d) 2x² + 3xy - 5y² = 2x² - 2xy + 5xy - 5y² = 2x( x - y ) + 5y( x - y ) = ( x - y )( 2x + 5y )

e) x² - 35y² - 2xy = x² + 5xy - 7xy - 35y² = x( x + 5y ) - 7y( x + 5y ) = ( x + 5y )( x - 7y )

f) 2x² + 10xy + 8y² = 2( x² + 5xy + 4y² ) = 2( x² + xy + 4xy + 4y² ) = 2[ x( x + y ) + 4y( x + y ) ] = 2( x + y )( x + 4y )

g) x² - 10xy + 16y² = x² - 2xy - 8xy + 16y² = x( x - 2y ) - 8y( x - 2y ) = ( x - 2y )( x - 8y )

h) 4x² + 4xy - 15y² = 4x² - 6xy + 10xy - 15y² = 4x( x - 3/2y ) + 10y( x - 2/3y ) = ( x - 2/3y )( 4x + 10y )

i) -7xy + 3x² + 2y² = 3x² - xy - 6xy + 2y² = 3x( x - 1/3y ) - 6y( x - 1/3y ) = ( x - 1/3y )( 3x - 6y )

j) 56y² + 4x² - 36xy = 4( x² - 9xy + 14y² ) = 4( x² - 2xy - 7xy + 14y² ) = 4[ x( x - 2y ) - 7y( x - 2y ) ] = 4( x - 2y )( x - 7y )

a/ = xy(5y - 6x)

b/ = - (15y² - 2x + 5y - 10xy)

\(=\frac{2x\left(x-2y\right)}{\left(x+2y\right)^2}:\frac{\left(2y-x\right)\left(2y+x\right)}{\left(x-2y\right)^2}:\frac{5xy\left(x-2y\right)}{\left(x+2y\right)^3}\)

Điều kiện: \(x\ne2y;x\ne-2y;x\ne0;y\ne0\)

\(=\frac{2x\left(x-2y\right)}{\left(x+2y\right)^2}:\frac{\left(2y+x\right)}{\left(x-2y\right)}:\frac{5xy\left(x-2y\right)}{\left(x+2y\right)^3}\)

\(=\frac{2x\left(x-2y\right)}{\left(x+2y\right)^2}\times\frac{x-2y}{x+2y}\times\frac{\left(x+2y\right)^3}{5xy\left(x-2y\right)}=\frac{2\left(x-2y\right)}{5y}\)

\(=\dfrac{2x\left(x-2y\right)}{\left(x+2y\right)^2}\cdot\dfrac{\left(x-2y\right)^2}{-\left(x-2y\right)\left(x+2y\right)}:\dfrac{5x^2y-10xy^2}{x^3+6x^2y+12xy^3+8y^3}\)

\(=\dfrac{-2x\left(x-2y\right)^2}{\left(x+2y\right)^3}\cdot\dfrac{\left(x+2y\right)^3}{5xy\left(x-2y\right)}\)

\(=\dfrac{-2x\cdot\left(x-2y\right)}{5xy}=\dfrac{-2\left(x-2y\right)}{5y}\)

làm ơn giúp e vs

\(1,=\left(x-2\right)\left(5-y\right)\\ 2,=2\left(x-y\right)^2-z\left(x-y\right)=\left(x-y\right)\left(2x-2y-z\right)\\ 3,=5xy\left(x-2y\right)\\ 4,=3\left(x^2-2xy+y^2-4z^2\right)=3\left[\left(x-y\right)^2-4z^2\right]\\ =3\left(x-y-2z\right)\left(x-y+2z\right)\\ 5,=\left(x+2y\right)^2-16=\left(x+2y-4\right)\left(x+2y+4\right)\\ 6,=-\left(6x^2-3x-4x+2\right)=-\left(2x-1\right)\left(3x-2\right)\\ 7,=\left(2x+y\right)\left(2x+y+x\right)=\left(2x+y\right)\left(3x+y\right)\\ 8,=\left(x-y\right)\left(x+5\right)\\ 9,=\left(x+1\right)^2-y^2=\left(x-y+1\right)\left(x+y+1\right)\\ 10,=\left(x^2-9\right)x=x\left(x-3\right)\left(x+3\right)\\ 11,=\left(x-2\right)\left(y+1\right)\\ 12,=\left(x-3\right)\left(x^2-4\right)=\left(x-3\right)\left(x-2\right)\left(x+2\right)\\ 13,=3\left(x+y\right)-\left(x+y\right)^2=\left(x+y\right)\left(3-x-y\right)\)