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12 tháng 9 2018

a ) x3 + 2x - 3

= x3 - x2 + x2 -  x + 3x - 3

= x2. ( x - 1 )  + x ( x - 1 ) + 3 . ( x  - 1 )

=   ( x - 1 ) ( x2 + x + 3 )

b ) x3 - 7x + 6

= x3 - x2 + x2 - x - 6x + 6 

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

= ( x - 1 ) ( x2 + x - 6 )

= ( x - 1 ) ( x2 - 2x + 3x - 6 )

= ( x - 1 ) [ x ( x - 2 ) + 3. ( x - 2 ) ]

= ( x - 1 ) ( x - 2 ) . ( x + 3 )

c ) x3 + 5x2 + 8x + 4

= x3 + x2 + 4x2 + 4x + 4x + 4

= x2 ( x + 1 )  + 4x ( x + 1 ) + 4 ( x + 1 )

= ( x + 1 ) . ( x2 + 4x + 4 )

= ( x + 1 ) . ( x + 2 )2

d ) x3 - 9x2 + 6x + 16 

= x3 + x2 - 10x2 - 10x + 16x + 16

= x2 ( x + 1 ) - 10x ( x + 1 ) + 16 ( x + 1 )

= ( x + 1 ) ( x2 - 10x + 16 )
= ( x + 1 ) ( x2 - 2x - 8x + 16 )

= ( x + 1 ) . [ x. ( x - 2 ) - 8 . ( x - 2 ) ]

= ( x + 1 ) . ( x - 2 ) . ( x - 8 )

e ) x3 - x2 - x - 2 

= x3 - 2x2 + x2 - 2x + x - 2 

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

= ( x - 2 ) ( x2 + x + 1 )

g ) x3 + x - x + 2

= x3 + 2x2 - x2 - 2x + x + 2

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

= ( x + 2 ) ( x2 - x + 1 ) 

h ) x3 - 6x2 - x + 30

= x3 + 2x2 - 8x2 - 16x + 15x + 30

= x2 ( x + 2 ) - 8x ( x + 2 ) + 15 ( x + 2 )

= ( x + 2 ) ( x2 - 8x + 15 )

= ( x + 2 ) ( x2 - 5x - 3x + 15 )

= ( x + 2 ) [ x ( x - 5 ) - 3 ( x - 5 ) ]

= ( x + 2 ) ( x - 5 ) ( x - 3 )

a ) x3 + 2x - 3

= x3 - x2 + x2 -  x + 3x - 3

= x2. ( x - 1 )  + x ( x - 1 ) + 3 . ( x  - 1 )

=   ( x - 1 ) ( x2 + x + 3 )

b ) x3 - 7x + 6

= x3 - x2 + x2 - x - 6x + 6 

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

= ( x - 1 ) ( x2 + x - 6 )

= ( x - 1 ) ( x2 - 2x + 3x - 6 )

= ( x - 1 ) [ x ( x - 2 ) + 3. ( x - 2 ) ]

= ( x - 1 ) ( x - 2 ) . ( x + 3 )

P/s tham khảo nha

4 tháng 8 2018

Ik mk nha, hôm nay ngày mai, ngày kia mk ik 3 lần lại cho bạn (thành 9 lần)

Nhớ kb với mìn lun nha!! Mk rất vui đc làm quen vs bạn, cảm ơn mn nhìu lắm

16 tháng 7 2018

1)  \(x^6-x^4-9x^3+9x^2\)

\(=x^2\left(x^4-x^2-9x+9\right)\)

\(=x^2\left[x^2\left(x^2-1\right)-9\left(x-1\right)\right]\)

\(=x^2\left(x-1\right)\left[x^2\left(x+1\right)-9\right]\)

\(=x^2\left(x-1\right)\left(x^3+x^2-9\right)\)

2)   \(x^4-4x^3+8x^2-16x+16\)

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

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

18 tháng 7 2018

3) \(x^4-25x^2+20x-4=x^4+5x^3-2x^2-5x^3-25x^2+10x+2x^2+10x-4\)

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

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

4) \(5x\left(x-2y\right)+2\left(2y-x\right)^2\)\(=5x\left(x-2y\right)+2\left(x-2y\right)^2=\left(x-2y\right)\left(5x+2x-4y\right)=\left(x-2y\right)\left(7x-4y\right)\)

5) \(x^2\left(x^2-6\right)-x^2+9=x^4-7x^2+9\)

\(=x^4+x^3-3x^2-x^3-x^2+3x-3x^2-3x+9\)

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

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

6) \(7x\left(y-4\right)^2-\left(4-y\right)^3=7x\left(y-4\right)^2+\left(y-4\right)^3=\left(y-4\right)^2\left(7x+y-4\right)\)

7) \(x^3+2x^2-6x-27=x^3-3x^2+5x^2-15x+9x-27\)

\(=x^2\left(x-3\right)+5x\left(x-3\right)+9\left(x-3\right)=\left(x-3\right)\left(x^2+5x+9\right)\)

24 tháng 6 2017

a) Ta có : x2 - 4x + 3

= x2 - x - 3x + 3

= x(x - 1) - (3x - 3) 

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

= (x - 1) (x - 3) 

24 tháng 6 2017

a) \(x^2-4x+3\)

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

\(=x\left(x-1\right)-3\left(x-1\right)\)

\(=\left(x-1\right)\left(x-3\right)\)

b) \(x^2+5x+4\)

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

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

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

c) \(x^2-x-6\)

\(=x^2-3x+2x-6\)

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

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

d) \(x^4+1997x^2+1996x+1997\)

\(=x^4+x^2+1996x^2+1996x+1996+1\)

\(=\left(x^4+x^2+1\right)+\left(1996x^2+1996x+1996\right)\)

\(=\left(x^2+x+1\right)\left(x^2-x+1\right)+1996\left(x^2+x+1\right)\)

\(=\left(x^2+x+1\right)\left(x^2-x+1997\right)\)

e) \(x^2-2001\cdot2002\)( hình như sai sai)

2 tháng 4 2020

a. x3+5x2+3x-9

= x3-x2+6x2-6x+9x-9

= x2(x-1)+6x(x-1)+9(x-1)

= (x2+6x+9)(x-1)

= (x+3)2(x-1)

b. x3+9x2+11x-21

= x3-x2+10x2-10x+21x-21

= x2(x-1)+10x(x-1)+21(x-1)

= (x2+10x+21)(x-1)

= (x+7)(x+3)(x-1)

c. x3-7x+6

= x3-x2+x2-x-6x+6

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

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

= (x+3)(x-2)(x-1)

d. x3-5x2+8x-4

= x3-x2-4x2+4x+4x-4

= x2(x-1)-4x(x-1)+4(x-1)

= (x2-4x+4)(x-1)

= (x-2)2(x-1)

e. x3-3x+2

= x3+2x2-2x2-4x+x+2

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

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

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

f. x3+8x2+17x+10

= x3+5x2+3x2+15x+2x+10

= x2(x+5)+3x(x+5)+2(x+5)

= (x2+3x+2)(x+5)

= (x+1)(x+2)(x+5)

g. x3+3x2+6x+4

= x3+x2+2x2+2x+4x+4

= x2(x+1)+2x(x+1)+4(x+1)

= (x2+2x+4)(x+1)

h. x3-2x-4

= x3-2x2+2x2-4x+2x-4

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

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

k. x3+x2+4

= x3+2x2-x2-2x+2x+4

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

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

l. x3-12x+7x-2

= x3+2x2-2x2-4x-x-2

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

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

2 tháng 4 2020

thansk you

15 tháng 8 2017

help me ,pleas?

12 tháng 9 2020

a. \(\left(x+y\right)^3+\left(x-y\right)^3\)

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

\(=2x^3+6xy^2\)

\(=2x\left(x^2+6y^2\right)\)

b. \(x^3-y^3+2x^2-2y^2\)

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

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

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

c. \(x^3-y^3-3x^2+3x-1\)

\(=\left(x^3-3x^2+3x-1\right)-y^3\)

\(=\left(x-1\right)^3-y^3\)

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

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