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6 tháng 1 2017

thay f(-2)

suy ra f(-2)=-117

thay g(-117)

suy ra g(-117)=-235

(2x-1)(27x3+27x2+9x+9)

= (2x-1)(3x+\(\sqrt{3}\))3

Thay x = -2 ta được

(2.2-1)(3.2+\(\sqrt{3}\))3

= -5 . -127= 635

27 tháng 11 2018

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

b. \(\left(x+1\right)^2-25=\left(x+1+5\right)\left(x+1-5\right)=\left(x+6\right)\left(x-4\right)\)

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

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

e. \(27+27x+9x^2+x^3=\left(x+3\right)^3\)

f, \(8x^3-12x^2y+6xy^2-y^3=\left(2x-y\right)^3\)

g, \(x^3+8y^3=\left(x+2y\right)\left(x^2-2xy+4y^2\right)\)

27 tháng 11 2018

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

\(\Leftrightarrow y^2-2y+1\)

\(\Leftrightarrow\left(y-1\right)^2\)

\(\left(b\right)\left(x+1\right)^2-25\)

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

\(\Leftrightarrow\left(x-4\right)\left(x+6\right)\)

\(\left(c\right)1-4x^2\)

\(\Leftrightarrow1-\left(2x\right)^2\)

\(\Leftrightarrow\left(1-2x\right)\left(1+2x\right)\)

\(\left(d\right)8-27x^3\)

\(\Leftrightarrow2^3-\left(3x\right)^3\)

\(\Leftrightarrow\left(2-3x\right)\left(4+6x+9x^2\right)\)

\(\left(e\right)27+27x+9x^2+x^3\)

\(\Leftrightarrow\left(x+3\right)^3\)

\(\left(f\right)8x^3-12x^2y+6xy^2-y^3\)

\(\Leftrightarrow\left(2x\right)^3-12x^2y+6xy^2-y^3\)

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

\(\left(g\right)x^3+8y^3\)

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

27 tháng 11 2018

a) 1 - 2y + y2

= (1-y)2

b) ( x + 1 )- 25

=( x + 1 )- 52

=(x+1+5)(x+1-5)

27 tháng 11 2018

c) 1 - 4x2

= 1- 2x2

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

AH
Akai Haruma
Giáo viên
29 tháng 1 2020

Lời giải:
f)

$2x^3+3x^2+3x+1=2x^3+x^2+2x^2+x+2x+1$

$=x^2(2x+1)+x(2x+1)+(2x+1)=(2x+1)(x^2+x+1)$

g)

$3x^3-2x^2+5x+2=3x^3+x^2-3x^2-x+6x+2$

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

h)

$27x^3-27x^2+18x-4=27x^3-9x^2-18x^2+6x+12x-4$

$=9x^2(3x-1)-6x(3x-1)+4(3x-1)=(3x-1)(9x^2-6x+4)$

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 )

a) Ta có: \(x^2+2x+1\)

\(=x^2+2\cdot x\cdot1+1^2\)

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

b) Ta có: \(1-2y+y^2\)

\(=y^2-2\cdot y\cdot1+1^2\)

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

c) Ta có: \(x^3-3x^2+3x-1\)

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

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

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

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

d) Ta có: \(27+27x+9x^2+x^3\)

\(=x^3+3x^2+6x^2+18x+9x+27\)

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

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

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

e) Ta có: \(8-125x^3\)

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

\(=\left(2-5x\right)\left(4+10x+25x^2\right)\)

f) Ta có: \(64x^3+\frac{1}{8}\)

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

\(=\left(4x+\frac{1}{2}\right)\left(16x^2-2x+\frac{1}{4}\right)\)

g) Ta có: \(1-x^2y^4\)

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

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

16 tháng 8 2020

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

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

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

d) \(27+27x+9x^2+x^3=3^3+3.3^2x+3.3x^2+x^3=\left(3+x\right)^3\)

e) \(8-125x^3=2^3-\left(5x\right)^3=\left(2-5x\right)\left[2^2+2.5x+\left(5x\right)^2\right]=\left(2-5x\right)\left(4+10x+25x^2\right)\)

f) \(64x^3+\frac{1}{8}=\left(4x\right)^3+\left(\frac{1}{2}\right)^3=\left(4x+\frac{1}{2}\right)\left[\left(4x\right)^2-4x.\frac{1}{2}+\left(\frac{1}{2}\right)^2\right]=\left(4x+\frac{1}{2}\right)\left(16x^2-2x+\frac{1}{4}\right)\)

Ko chắc ạ!

Bài 1:

\(B=\dfrac{1}{9}x^2-2x+9\)

\(=\left(\dfrac{1}{3}x\right)^2-2\cdot\dfrac{1}{3}x\cdot3+3^2=\left(\dfrac{1}{2}x-3\right)^2\)

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

\(D=27x^3+27x^2+9x+1=\left(3x+1\right)^3\)

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

27 tháng 8 2021

Mik mới bít ý b thôi , còn ý a mik đang nghĩ nha ^^

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