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28 tháng 10 2017

a) 9x (3x-y) +3y (y-3x)

= 9x(3x-y)-3y(3x-y)

=(3x-y)(9x-3y)

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

= 3(3x-y)2

b)x3 - 3x2 - 9x + 27

=x3+3x2-6x2-18x+9x+27

= (x3+3x2)-(6x2+18x)+(9x+27)

= x2(x+3)-6x(x+3)+9(x+3)

= (x+3)(x2-6x+9)

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

28 tháng 10 2017

a) \(9x\left(3x-y\right)+3y\left(y-3x\right)=9x\left(3x-y\right)-3y\left(3x-y\right)\)

=\(\left(3x-y\right)\left(9x-3y\right)\)

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

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

b) \(x^3-3x^2-9x+27=\left(x^3-3x^2\right)-\left(9x-27\right)\)

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

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

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

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

4 tháng 11 2016

1.

a) \(\left(-2x^3\right)\)\(\left(x^2+5x-\frac{1}{2}\right)\) = \(-2x^5\)\(-10x^4\) \(+x^3\)

b) (\(6x^3-7x^2\)\(-x+2\))\(:\left(2x+1\right)\)=\(3x^2-5x+2\)

2.

a) 9x(3x-y) + 3y (y-3x)=9x(3x-y)-3y(3x-y)

= (9x-3y)(3x-y)

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

= 3(3x-y)^2

b) \(x^3-3x^2\)\(-9x+27\)= \(\left(x^3-3x^2\right)\)\(-\left(9x-27\right)\)

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

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

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

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

4 tháng 11 2016

Bài 1 ) a ) \(\left(-2x^3\right)\left(x^2+5x-\frac{1}{2}\right)\)

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

b ) \(\left(6x^3-7x^2+x+2\right):\left(2x+1\right)\)

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

2 ) a ) \(9x\left(3x-y\right)+3y\left(y-3x\right)\)

\(=9x\left(3x-y\right)-3y\left(3x-y\right)\)

\(=\left(3x-y\right)\left(9x-3y\right)\)

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

b ) \(x^3-3x^2-9x+27\)

\(=\left(x^3-3x^2\right)-\left(9x-27\right)\)

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

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

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

 

 

 

19 tháng 12 2018

a)\(3.3x^3+9x\)

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

b) \(xy+y^2-3x-3y\)

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

19 tháng 12 2018

\(3x^33+9x=9x\left(x^2+1\right)\)

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

15 tháng 7 2016

a)x3+3x2+3x+1

=x3+3x2*1+3x*12+13

=(x+1)3

b)(x+y)2-9x2

=y2+2xy+x2-9x2

=y2-2xy+4xy-8x2

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

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

16 tháng 11 2018

b.10x(x-y)-6y(y-x)=10x(x-y)+6y(x-y)=(10x+6y)(x-y)

16 tháng 11 2018

c.3x2+5y-3xy-5x=(3x2--3xy)-(5x-5y)=3x(x-y)-5(x-y)=(3x-5)(x-y)

14 tháng 8 2015

a/ \(=3y^2-6y-2x+1\)

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

c/ \(=\left(2-x\right)^3\)

d/ \(=xy^2+x^2y+3xy+x^2y+x^3+3x^2-3xy-3x^2-9x\)

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

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

e/ \(=xy-x^2+2x-y^2+xy-2y\)

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

14 tháng 8 2015

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

b)=-(x-1)3

c)=-(x3-6x2+12x-8)=-(x-2)3

d)x3 + 2x2y + xy2 – 9x

    = x(x2 + 2xy + y2 -9)

    = x[(x2 + 2xy + y2) - 32]

    = x[(x + y)2 - 32]

    = x (x + y – 3)(x + y + 3)

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

10 tháng 10 2021

\(a)\) \(3x^2-6x=3x\left(x-2\right)\)

\(b)\) \(9x^3-9x^2y-4x+4y\)

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

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

\(=[\left(3x\right)^2-2^2]\left(x-y\right)\)

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

\(c)\) \(x^3-2x^2-8x\)

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

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

4 tháng 7 2017

bn chép lại đề nha 

a/ \(=a^3+1-a^2x-ax\)

\(=\left(a+1\right)\left(a^2-a+1\right)-ax\left(a+1\right)\)

\(=\left(a+1\right)\left(a^2-a+1-ax\right)\)

b/ bn có chép sai đề không? mình sửa lại dấu "-" rồi nha \(-3x^2y\)

 \(=12y+36-9x^2-3x^2y=12\left(y+3\right)-3x^2\left(y+3\right)\)

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