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7 tháng 10 2019

Bài 1:

a) \(25-x^2+2xy-y^2=25-\left(x^2-2xy+y^2\right)\)

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

b) \(18-x^2+12xz-9z^2\): không thể phân tích thành nhân tử

c) Không thể phân tích thành nhân tử.

d) \(16-x^2-2xy-y^2=4^2-\left(x^2+2xy+y^2\right)\)

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

e) Sử đề \(x^2+2xy+y^2-z^2-4zt-4t^2\)

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

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

f) \(x^4+4=x^4+4x^2+4-4x^2\)

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

g) \(x^4+64=x^4+16x^2+64-16x^2\)

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

h) \(x^4+36x^2+324-36x^2\)

\(=\left(x^2+18\right)^2-\left(6x\right)^2=\left(x^2-6x+18\right)\left(x^2+6x+18\right)\)

12 tháng 9 2020

a) x2 - y2 + 4x + 4

= ( x2 + 4x + 4 ) - y2

= ( x + 2 )2 - y2

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

b) x2 - 2xy + y2 - 1

= ( x2 - 2xy + y2 ) - 1

= ( x - y )2 - 12

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

c) x2 - 2xy + y2 - 4

= ( x2 - 2xy + y2 ) - 4

= ( x - y )2 - 22

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

d) x2 - 2xy + y2 - z2

= ( x2 - 2xy + y2 ) - z2

= ( x - y )2 - z2

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

e) 25 - x2 + 4xy - 4y2

= 25 - ( x2 - 4xy + 4y2 )

= 52 - ( x - 2y )2

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

f) x2 + y2 - 2xy - 4z2

= ( x2 - 2xy + y2 ) - 4z2

= ( x - y )2 - ( 2z )2

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

3 tháng 10 2016

x6+3x4y2-8x3y3+3x2y4+y6= x6+3x4y2+3x2y4+y6-8x3y3=(x2+y2)3-(2xy)3

= (x2+y2-2xy)[(x2+y2)2+2xy(x2+y2)+(2xy)2]= (x-y)2(x4+6x2y2+y4+2x3y+2xy3)

(x2+y2-5)2-4x2y2-16xy-16=(x2+y2-5)2-(4x2y2+16xy+16)=(x2+y2-5)2-(2xy+4)2

=(x2+y2-5+2xy+4)(x2+y2-5-2xy-4)=(x2+2xy+y2-1)(x2-2xy+y2-9)=[(x+y)2-1][(x-y)2-32]=(x+y-1)(x+y+1)(x-y-3)(x-y+3)

x4+324=x4+36x2+324-36x2=(x2+18)2-(6x)2=(x2+18-6x)(x2+18+6x)

 

21 tháng 6 2017

A = x2(x - 1) + 6(1 - x)

A = x3 - x2 + 6 - 6x

A = (x3 - 6x) - (x2 - 6)

A = x.(x2 - 6) - (x2 - 6)

A = (x - 1)(x2 - 6)

21 tháng 6 2017

C = x2 + 2xy + y2 - yz - xz

C = (x + y)2 - z.(x + y)

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

12 tháng 8 2015

a) x^4 - x^3 - x + 1 

= x^3 ( x - 1 ) - ( x- 1 )

= ( x^3 - 1 )(x - 1)

= ( x- 1 )^2 (x^2 + x +  1 )

 

12 tháng 8 2015

a)x4-x3-x+1

=x3(x-1)-(x-1)

=(x-1)(x3-1)

=(x-1)(x-1)(x2+x+1)

=(x-1)2(x2+x+1)

b)5x2-4x+20xy-8y

(sai đề)

 

16 tháng 7 2017

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

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

b)  \(x^4-6x^3+54x-81=\left(x^4-81\right)-\left(6x^3-54x\right)=\left(x^2-9\right)\left(x^2+9\right)-6x.\left(x^2-9\right)\)

\(=\left(x^2-9\right).\left(x^2+9-6x\right)=\left(x+3\right).\left(x-3\right).\left(x-3\right)^2=\left(x+3\right).\left(x-3\right)^3\)

c)  \(ax^2+ax-bx^2-bx-a+b=\left(ax^2-bx^2\right)+\left(ax-bx\right)-\left(a-b\right)\)

\(=x^2.\left(a-b\right)+x.\left(a-b\right)-\left(a-b\right)=\left(a-b\right).\left(x^2+x-1\right)\)

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

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

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

9 tháng 10 2020

a) 36 - 4a2 + 20ab - 25b2 = 36 - ( 4a2 - 20ab + 25b2 ) = 62 - ( 2a - 5b )2 = ( 6 - 2a + 5b )( 6 + 2a - 5b )

b) ( xy + 4 )2 - 4( x + y )= ( xy + 4 )2 - 22( x + y )2 = ( xy + 4 )2 - [ 2( x + y ) ]2 

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

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

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

c) x2 + y2 - x2y2 + xy - x - y

= ( x2 - x2y2 ) + ( y2 - y ) + ( xy - x )

= x2( 1 - y2 ) + y( y - 1 ) + x( y - 1 )

= x2( 1 - y )( 1 + y ) - y( 1 - y ) - x( 1 - y )

= ( 1 - y )[ x2( 1 + y ) - y - x ) ]

= ( 1 - y )( x2 + x2y - y - x )

= ( 1 - y )[ ( x2 - x ) + ( x2y - y ) ]

= ( 1 - y )[ x( x - 1 ) + y( x2 - 1 ) ]

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

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

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

d) 3x + 3y - x2 - 2xy - y2

= 3( x + y ) - ( x2 + 2xy + y2 )

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

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

e) ( 2xy + 1 )2 - ( 2x + y )2

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

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

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

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

9 tháng 10 2020

a) \(36-4a^2+20ab-25b^2\)

\(=36-\left(4a^2-20ab+25b^2\right)\)

\(=36-\left(2a-5b\right)^2\)

\(=\left(6-2a+5b\right)\left(6+2a-5b\right)\)

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

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

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

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

c) \(x^2+y^2-x^2y^2+xy-x-y\)

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

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

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

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

\(=\left(1-y\right)\left(x-1\right)\left(xy+y+x\right)\)