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14 tháng 10 2020

1) \(4x^2-7x-2=4x^2-8x+x-2=\left(4x^2-8x\right)+\left(x-2\right)\)

\(=4x\left(x-2\right)+\left(x-2\right)=\left(x-2\right)\left(4x+1\right)\)

2) \(4x^2+5x-6=4x^2+8x-3x-6=\left(4x^2+8x\right)-\left(3x+6\right)\)

\(=4x\left(x+2\right)-3\left(x+2\right)=\left(x+2\right)\left(4x-3\right)\)

3) \(5x^2-18x-8=5x^2-20x+2x-8=\left(5x^2-20x\right)+\left(2x-8\right)\)

\(=5x\left(x-4\right)+2\left(x-4\right)=\left(x-4\right)\left(5x+2\right)\)

4) \(xy\left(x+y\right)-yz\left(y+z\right)+xz\left(x-z\right)\)

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

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

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

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

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

\(=\left(x+y\right)\left(xy+xz-yz-z^2\right)=\left(x+y\right).\left[x\left(y+z\right)-z\left(y+z\right)\right]\)

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

14 tháng 10 2020

1) 4x2 - 7x - 2 = 4x2 - 8x + x - 2 = 4x( x - 2 ) + ( x - 2 ) = ( x - 2 )( 4x + 1 )

2) 4x2 + 5x - 6 = 4x2 - 8x + 3x - 6 = 4x( x - 2 ) + 3( x - 2 ) = ( x - 2 )( 4x + 3 )

3) 5x2 - 18x - 8 = 5x2 - 20x + 2x - 8 = 5x( x - 4 ) + 2( x - 4 ) = ( x - 4 )( 5x + 2 )

4) xy( x + y ) - yz( y + z ) + xz( x - z )

= x2y + xy2 - y2z - yz2 + xz( x - z )

= ( x2y - yz2 ) + ( xy2 - y2z ) + xz( x - z )

= y( x2 - z2 ) + y2( x - z ) + xz( x - z )

= y( x - z )( x + z ) + y2( x - z ) + xz( x - z )

= ( x - z )[ y( x + z ) + y2 + xz ]

= ( x - z )( xy + yz + y2 + xz )

= ( x - z )[ ( xy + y2 ) + ( xz + yz ) ]

= ( x - z )[ y( x + y ) + z( x + y ) ]

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

5) xy( x + y ) + yz + xz( x + z ) + 2xyz ( đề có thiếu không vậy .-. )

14 tháng 9 2016

x2 - x - y2 - y

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

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

***

9x2 + y2 - 16z2 + 6xy

= (3x + y)2 - (4z)2

= (3x + y - 4z)(3x + y + 4z)

***

a3 - a2x - ay + xy

= a2(a - x) - y(a - x)

= (a - x)(a2 - y)

***

2x2 - 8y2 + 3x + 6y

= 2(x2 - 4y2) + 3(x + 2y)

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

= (x + 2y)(2x - 4y + 3)

***

xy(x + y) + yz(y + z) + xz(x + z) + 2xyz

= xy(x + y + z) + yz(x + y + z) + xz(x + z)

= y(x + y + z)(x + z) + xz(x + z)

= (x + z)(xy + y2 + yz + xz)

= (x + z)[y(x + y) + z(x + y)]

= (x + z)(x + y)(y + z) 

11 tháng 8 2018

Vụ này khoai à nha !

11 tháng 8 2018

\(b,9x^2+90x+225-\left(x-y\right)^2\)

\(=\left(3x+15\right)^2-\left(x-y\right)^2\)

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

\(=\left(2x+y+15\right)\left(4x-y+15\right)\)

13 tháng 12 2018

\(2xyz+x^2y+xy^2+x^2z+xz^2+y^2z+yz^2\)

\(=x^2\left(y+z\right)+yz\left(y+z\right)+x\left(y^2+z^3\right)+2xyz\)

\(=\left(y+z\right)\left(x^2+yz\right)+x\left(y^2+z^2+2yz\right)\)

\(=\left(y+z\right)\left(x^2+yz\right)+x\left(y+z\right)^2\)

\(=\left(y+z\right)\left(x^2+yz\right)+xy+xz\)

\(=\left(y+z\right)\left[x\left(x+2\right)+y\left(x+2\right)\right]\)

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

13 tháng 12 2018

\(b,x^2\left(y-z\right)+y^2\left(z-y\right)+z^2\left(x-y\right)\)

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

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

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

\(=\left(y-z\right)\left[x\left(x-y\right)-z\left(x-y\right)\right]\)

\(=\left(y-z\right)\left[\left(x-z\right)\left(x-y\right)\right]\)

2 tháng 9 2018

\(yz\left(y+z\right)+zx\left(z-x\right)-xy\left(x+y\right)\)

\(=yz\left(y+z\right)+zx\left(z-x\right)-xy\left[\left(y+z\right)-\left(z-x\right)\right]\)

\(=yz\left(y+z\right)+zx\left(z-x\right)-xy\left(y+z\right)+xy\left(z-x\right)\)

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

\(=\left(z-x\right)\left(yz-xy+xz-xy\right)\)