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28 tháng 2 2020

\(27^x=3^{x+2}\)

\(\Leftrightarrow3^{3x}=3^{x+2}\)

\(\Leftrightarrow3x=x+2\)

\(\Leftrightarrow2x=2\)

\(\Leftrightarrow x=1\)

28 tháng 2 2020

27x=3x+2

33x=3x+2

3x=x+2

3x-x=2 (quy tắc chuyển vế)

2x=2

x=2:2

x=1 

Vậy: x=1

(éc=1).

13 tháng 11 2021

C

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

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

c) \(-8+12x-6x^2+x^3=\left(x-2\right)^3\)

\(\dfrac{3x^3+2x^2-27x}{-3x}=\dfrac{-3x^3}{3x}-\dfrac{2x^2}{3x}+\dfrac{27x}{3x}=-x^2-\dfrac{2}{3}x+9\)

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

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

=>\(\left(3x^2+1\right)^2+4x\left(3x^2+1\right)-5x^2-27x^2=0\)

=>\(\left(3x^2+1\right)^2+4x\left(3x^2+1\right)-32x^2=0\)

=>\(\left(3x^2+1+8x\right)\left(3x^2+1-4x\right)=0\)

=>\(\left(3x^2+8x+1\right)\left(3x-1\right)\left(x-1\right)=0\)

=>\(\left[{}\begin{matrix}3x^2+8x+1=0\\3x-1=0\\x-1=0\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=1\\x=\dfrac{-4\pm\sqrt{13}}{3}\end{matrix}\right.\)

a: \(=\left(x+1+5\right)\left(x+1-5\right)=\left(x+6\right)\left(x-4\right)\)

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

c: \(=\left(2-3x\right)\left(4+6x+9x^2\right)\)

d: =(x+3)^3

e: \(=\left(2x-y\right)^3\)

f: =(x+2y)(x^2-2xy+4y^2)

a: x^3-7x-6

=x^3-x-6x-6

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

=(x+1)(x^2-x-6)

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

b: =2x^3+x^2-2x^2-x+6x+3

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

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

c: =2x^3-3x^2-2x^2+3x+2x-3

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

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

d: =2x^3+x^2+2x^2+x+2x+1

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

e: =3x^3+x^2-3x^2-x+6x+2

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

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

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

29 tháng 8 2023

a) \(x^3-7x-6\)

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

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

\(=x\left(x^2-1\right)-6\left(x+1\right)\)

\(=x\left(x+1\right)\left(x-1\right)-6\left(x+1\right)\)

\(=\left(x+1\right)\left(x^2-x-6\right)\)

b) \(2x^3-x^2+5x+3\)

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

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

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

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

c) \(2x^3-5x^2+5x+1\)

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

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

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

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

d) \(2x^3+3x^2+3x+1\)

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

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

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

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

e) \(3x^3-2x^2+5x+2\)

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

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

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

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

f) \(27x^3-27x^2+18x-4\)

\(=27x^3-9x^2-18x^2+6x+12x-4\)

\(=\left(27x^3-9x^2\right)-\left(18x^2-6x\right)+\left(12x-4\right)\)

\(=9x^2\left(3x-1\right)-6x\left(3x-1\right)+4\left(3x-1\right)\)

\(=\left(3x-1\right)\left(9x^2-6x+4\right)\)

b: \(x^3+\dfrac{1}{27}=\left(x+\dfrac{1}{3}\right)\left(x^2-\dfrac{1}{3}x+\dfrac{1}{9}\right)\)

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

e: \(a^2y^2-2axby+b^2x^2\)

\(=\left(ay\right)^2-2\cdot ay\cdot bx+\left(bx\right)^2\)

\(=\left(ay-bx\right)^2\)

f: \(100-\left(3x-y\right)^2\)

\(=\left(10-3x+y\right)\left(10+3x-y\right)\)

g: \(64x^2-\left(8a+b\right)^2\)

\(=\left(8x\right)^2-\left(8a+b\right)^2\)

\(=\left(8x-8a-b\right)\left(8x+8a+b\right)\)

5 tháng 11 2023

    3\(x^2\) - 27\(x\) + 6\(x^3\)

= 3\(x\).(\(x\) - 9\(x\) + 2\(x^2\))

 

5 tháng 11 2023

3x2 - 27x + 6x3 : 

= 3x(x2- 9 + 2x2)

3 tháng 8 2023

a) 9x4+16y6-24x2y3

=(3x2)2-2.3x2.4y3+(4y3)2

=(3x2-4y3)2

b) 16x2-24xy+9y2

=(4x)2-2.4x.3y+(3y)2

=(4x-3y)2

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

=(36x-3x+2)(36x+3x-2)

=(33x+2)(39x-2)

d) 27x3+54x2y+36xy2+8y3

=(3x)3+3.(3x)2.2y+3.3x.(2y)2+(2y)3

=(3x+2y)3

e) y9-9x2y6+27x4y3-27x6

=(y3)3-3.(y3)2.3x2+3.y3.(3x2)2-(3x2)3

=(y3-3x2)3

f) 64x3+1

= (4x)3+13

=(4x+1)[(4x)2-4x.1+12]

=(4x+1)(16x2-4x+1)

e) 27x6-8x3  *sửa đề*

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

=(3x2-2x)[(3x)2+3x2.2x+(2x)2]

=(3x2-2x)(9x2+6x3+4x2)

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