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11 tháng 8 2016

17) \(8x^3+27=\left(2x\right)^3+3^3=\left(2x+3\right)\left(4x^2-6x+9\right)\)

18) \(a^6-1=\left(a^3\right)^2-1=\left(a^3-1\right)\left(a^3+1\right)=\left(a-1\right)\left(a^2+a+1\right)\left(a+1\right)\left(a^2-a+1\right)\)

20) \(9x^4-81x^2=9\left(x^4-9x^2\right)=9x^2\left(x^2-9\right)=9x^2\left(x-3\right)\left(x+3\right)\)

11 tháng 8 2016

17)

\(8x^3+27=\left(8x\right)^3+3^3=\left(8x+3\right)\left(64x^2-24x+9\right)\)

18)

\(a^6-1=\left(a^3\right)^2-1\)

\(=\left(a^3-1\right)\left(a^3+1\right)\)

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

19)

đề sao sao ý

20)

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

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

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

29 tháng 10 2016

đăng ít 1 thôi

30 tháng 10 2016

1. 8 - 12x + 6x2 - x3

= 23 - 3.22.x + 3.x2.2 - x3

=(2-x)3

2. 125x3 - 75x2 +15x - 1

=(5x)3 - 3.(5x)2.1 + 3.5x.12 - 13

=(5x - 1)3

3, 4 (sai đề)

5. x3 + 2x2 - 6x - 27

=(x3 - 27) + (2x2 - 6x)

=(x3 - 33) + (2x2 - 6x)

=(x -3)(x2 + 3x + 9) + 2x(x-3)

=(x-3)(x2 + 3x +9 +2x)

=(x-3)(x2 + 5x +9)

6. 12x3 + 4x2- 27x -9

=(12x3 + 4x2) - (27x + 9)

=4x2(3x + 1) - 9(3x +1)

=(3x -1)(4x2 -9)

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

 

1 tháng 11 2019

A.5X2+3(X+Y)2-5Y2

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

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

= ( x+y).[(5.( x-y) + 3(x+y)]

=( x+y).( 5x-5y +3x + 3y)

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

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

C.81x2 - 6yz - 9y2 - z2

=( 9x)2 - (z2 + 6yz+ 9y2)

=( 9x)2 -( z +3y)2

=(9x - z -3y).(9x + z+3y)

D.x2y-x3-9y+9x

=9.(x - y) + x2(y - x)

= 9.(x-y) - x2(x-y)

=(x+y).[32- x2]

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

E.x3+9x2-4x-36

=(x3-4x) + (-36 +9x2)

=x.(x2-4) + 9.(x2-4)

=(x2-4).(x+9)

H.2x3+x2-8x-4

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

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

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

Cậu xem trước nhé

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

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

10 tháng 7 2017

1, \(x^3+8x^2+17x+10=\left(x^3+x^2\right)+\left(7x^2+7x\right)+\left(10x+10\right)\)

\(=x^2\left(x+1\right)+7x\left(x+1\right)+10\left(x+1\right)\)\(=\left(x+1\right)\left(x^2+7x+10\right)=\left(x+1\right)\left(x+2\right)\left(x+5\right)\)

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

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

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

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

4. \(81x^4+4=\left(9x^2\right)^2+2^2=\left(9x^2+2\right)^2-2.9x^2.2=\left(9x^2+2\right)^2-\left(6x\right)^2\)

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

1 tháng 10 2016

\(3x^4+2x^3-8x^2-2x+5\)

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

\(=3x^3\left(x-1\right)+5x^2\left(x-1\right)-3x\left(x-1\right)-5\left(x-1\right)\)

\(=\left(3x^3+5x^2-3x-5\right)\left(x-1\right)\)

\(=\left[3x\left(x^2-1\right)+5\left(x^2-1\right)\right]\left(x-1\right)\)

\(=\left(3x+5\right)\left(x^2-1\right)\left(x-1\right)\)

\(=\left(3x+5\right)\left(x+1\right)\left(x-1\right)\left(x-1\right)=\left(3x+5\right)\left(x+1\right)\left(x-1\right)^2\)

b, \(2x^4-9x^3+4x^2+21x-18\)

\(=2x^4-2x^3-7x^3+7x^2-3x^2+3x+18x-18\)

\(=2x^3\left(x-1\right)-7x^2\left(x-1\right)-3x\left(x-1\right)+18\left(x-1\right)\)

\(=\left(2x^3-7x^2-3x+18\right)\left(x-1\right)\)

1 tháng 10 2016

asdf kien

14 tháng 7 2017

a) \(-x^3+9x^2-27x+27=-\left(x^3-3.3.x^2+3.3^2.x-3^3\right)=-\left(x-3\right)^3\)

b)\(x^4-2x^3-x^2+2x+1=x^4+\left(-x\right)^2+\left(-1\right)^2+2x^2\left(-x\right)+2.\left(-x\right).\left(-1\right)+2x^2.\left(-1\right)\)

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

c)\(8x^3+27y^3+36x^2y+54xy^2=\left(2x\right)^3+3.\left(2x\right)^2.3y+3.2x.\left(3y\right)^2+\left(3y\right)^3\)

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