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1 tháng 7 2015

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

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

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

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

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

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

19 tháng 9 2018

a ) 36x2 - ( 3x - 2 )2 

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

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

b ) 16.( 4x + 5 )2 - 25. ( 2x + 2 )2

= [ 4.( 4x + 5 ) + 5. ( 2x + 2 ) ] [ 4 .( 4x + 5 ) - 5. ( 2x + 2 ) ]

= ( 16x + 5 + 10x + 10 ) ( 16x + 5 - 10x - 10 )
= ( 26x + 15 ) ( 6x - 5 )

a ) 36x2 - ( 3x - 2 )2

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

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

b ) 16.( 4x + 5 )2 - 25. ( 2x + 2 )2

= [ 4.( 4x + 5 ) + 5. ( 2x + 2 ) ] [ 4 .( 4x + 5 ) - 5. ( 2x + 2 ) ]

= ( 16x + 5 + 10x + 10 ) ( 16x + 5 - 10x - 10 )

= ( 26x + 15 ) ( 6x - 5 )

13 tháng 9 2020

a) \(x^6-y^6=\left(x^3-y^3\right)\left(x^3+y^3\right)=\left(x+y\right)\left(x-y\right)\left(x^2-xy+y^2\right)\left(x^2+xy+y^2\right)\)

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

c) \(x^4-27x=x\left(x^3-27\right)=x\left(x-3\right)\left(x^2+3x+9\right)\)

d) \(27x^5+x^2=x^2\left(27x^3+1\right)=x^2\left(3x+1\right)\left(9x^2-3x+1\right)\)

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

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

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

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

30 tháng 7 2018

b)  \(64x^3+1=\left(4x+1\right)\left(16x^2-4x+1\right)\)\

c) \(x^3y^6z^9-125=\left(xy^2z^3-5\right)\left(x^2y^4z^6+5xy^2z+25\right)\)

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

e)  \(x^6-y^6=\left(x^3-y^3\right)\left(x^3+y^3\right)=\left(x-y\right)\left(x^2+xy+y^2\right)\left(x+y\right)\left(x^2-xy+y^2\right)\)

64x3 + 1

= ( 4x )3  +  1

= ( 4x + 1 ) ( 16x2 - 4x + 1 )

Hằng đẳng thức 6 : A3 + B3

27x6 - 8x3

= ( 3x2)3 + ( 2x )3

= ( 3x + 2x ) ( 9x2 - 6x + 4x2 )

HĐT 6

x6 - y6

= ( x2 )3 - ( y2 )3

= ( x2 - y2 ) ( x4 + x2y2 + y4 )

HĐT 7 : A3 - B3

x3y6z9 + 1

= ( xy2z3)3 + 1

= ( xy2z3 + 1 ) ( x2y4z6 + zy2z3 + 1 )

HĐT 6