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27 tháng 11 2020

\(\left(\frac{3x}{1-3x}+\frac{2x}{3x+1}\right)\div\frac{6x^2+10x}{1-6x+9x^2}\)

\(=\left(\frac{-3x}{3x-1}+\frac{2x}{3x+1}\right)\div\frac{2x\left(3x+5\right)}{9x^2-6x+1}\)

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

\(=\left(\frac{-9x^2-3x}{\left(3x-1\right)\left(3x+1\right)}+\frac{6x^2-2x}{\left(3x-1\right)\left(3x+1\right)}\right)\div\frac{2x\left(3x+5\right)}{\left(3x-1\right)^2}\)

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

\(=\frac{-x\left(3x+5\right)\times\left(3x-1\right)^2}{\left(3x-1\right)\left(3x+1\right)\times2x\left(3x+5\right)}\)

\(=\frac{-\left(3x-1\right)}{2\left(3x+1\right)}=\frac{-3x+1}{6x+2}\)

15 tháng 7 2021

A = ( 3x )3 + 23 - 27x3 + 6 = 27x3 + 8 - 27x3 + 6 = 14 ( đpcm )

B = x3 + 3x2 + 3x + 1 - ( x3 - 1 ) - 3x2 - 3x = x3 + 1 - x3 + 1 = 2 ( đpcm )

C = 6( x + 2 )( x2 - 2x )( x2 - 2x + 4 ) - 6x3 - 2 ( bạn xem lại đề bài nhé ._. )

D = 2[ ( 3x )3 + 13 ] - 54x3 = 2( 27x3 + 1 ) - 54x3 = 54x3 + 2 - 54x3 = 2 ( đpcm )

NV
20 tháng 12 2022

ĐKXĐ: \(x\ne\left\{-\dfrac{1}{3};\dfrac{1}{3};0;-\dfrac{4}{3}\right\}\)

\(M=\left(\dfrac{3x\left(1+3x\right)}{\left(1-3x\right)\left(1+3x\right)}+\dfrac{2x\left(1-3x\right)}{\left(1-3x\right)\left(1+3x\right)}\right):\dfrac{2x\left(3x+5\right)}{\left(1-3x\right)^2}\)

\(=\left(\dfrac{x\left(3x+5\right)}{\left(1-3x\right)\left(1+3x\right)}\right).\dfrac{\left(1-3x\right)^2}{2x\left(3x+5\right)}\)

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

24 tháng 12 2022

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4 tháng 10 2021

1, \(3x\left(x-7\right)+2x-14=0\)

\(\Rightarrow3x\left(x-7\right)+2\left(x-7\right)=0\)

\(\Rightarrow\left(x-7\right)\left(3x+2\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x=7\\x=\frac{-2}{3}\end{cases}}\)

2, \(x^3+3x^2-\left(x+3\right)=0\)

\(\Rightarrow x^2\left(x+3\right)-\left(x+3\right)=0\)

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

\(\Rightarrow\left(x+3\right)\left(x-1\right)\left(x+1\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x=-3\\x=\pm1\end{cases}}\)

3, \(15x-5+6x^2-2x=0\)

\(\Rightarrow\left(15x-5\right)+\left(6x^2-2x\right)=0\)

\(\Rightarrow5\left(3x-1\right)+2x\left(3x-1\right)=0\)

\(\Rightarrow\left(3x-1\right)\left(5+2x\right)=0\)

\(\Rightarrow\orbr{\begin{cases}3x-1=0\\5+2x=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{1}{3}\\x=\frac{-5}{2}\end{cases}}\)

4, \(5x-2-25x^2+10x=0\)

\(\Rightarrow\left(5x-25x^2\right)-\left(2-10x\right)=0\)

\(\Rightarrow5x\left(1-5x\right)-2\left(1-5x\right)=0\)

\(\Rightarrow\left(1-5x\right)\left(5x-2\right)=0\)

\(\Rightarrow\orbr{\begin{cases}1-5x=0\\5x-2=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{1}{5}\\x=\frac{2}{5}\end{cases}}\)

31 tháng 10 2021
(3x-2)(2x-4)=1-12x²
3 tháng 8 2018

b, x = -5/3 hoặc x = 4/3.

c, x = 0 hoặc x = 3, -3.

d, x = 0 hoặc x = 2, -2.

e, x = 1 hoặc x = \(\dfrac{-1}{2}\).

a: \(\Leftrightarrow x^2-40x+400-x^2-4x-3=-7\)

=>-44x+397=-7

=>-44x=-404

hay x=101

b: \(\Leftrightarrow\left[{}\begin{matrix}3x+5=0\\4-3x=0\end{matrix}\right.\Leftrightarrow x\in\left\{-\dfrac{5}{3};\dfrac{4}{3}\right\}\)

c: \(\Leftrightarrow x\left(x^2-9\right)=0\)

=>x(x-3)(x+3)=0

hay \(x\in\left\{0;3;-3\right\}\)

d: \(\Leftrightarrow x\left(x-2\right)\left(x+2\right)=0\)

hay \(x\in\left\{0;2;-2\right\}\)

e: =>(2x+1)(1-x)=0

=>x=-1/2 hoặc x=1

2 tháng 8 2018

(x + 2)(x - 2) - (x - 2)(x + 5)

= (x - 2)(x + 2 - x - 5)

= (x - 2)-3

= -3x + 6

b) 2x(3x2y + 4x2y - 3)

= 2x(7x2y - 3)

= 14x3y - 6x

2 tháng 8 2018

bạn giải hết đc ko ạ

6 tháng 8 2021

1, \(5x^2+10x+5-5y^2=5\left(x^2+2x+1-y^2\right)\)

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

2, \(3x^3+6x^2+3x-12xy^2=3x\left(x^2+2x+1-4y^2\right)\)

\(=3x\left[\left(x+1\right)^2-4y^2\right]=3x\left(x+1-2y\right)\left(x+1+2y\right)\)

3 tháng 8 2018

a) (x+2)(x-2) - (x-2)(x+5 )

= (x-2) (x+2 - x-5)

= -3 (x-2)

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

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

= 5x (x +2)

d) \(x^2\) - 4 - \(\left(x+2\right)^2\)

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

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

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

= -4 (x+2)

e: \(=x^2-16-2x^2-6x+x^2+6x+9=-7\)

b: \(=\left(6x+1-6x+1\right)^2=2^2=4\)