12x/6 + 4x/6 - 3x/6 = 3/8 - 1/4 - 1/6

13x/6 = (9 - 6 - 4)/24 = -1/24

--> x = -1/52

Lời giải:

$(6x)^3:8=(2x-1)^3$

$\Rightarrow (\frac{6x}{2})^3=(2x-1)^3$

$\Rightarrow (3x)^3=(2x-1)^3$

$\Rightarrow 3x=2x-1$

$\Rightarrow x=-1$

i dont no ok

B, => 2x+5=3x-8

2x-3x=-8-5

-x=-13

=>x=13

hoặc 2x+5=-3x+8

2x+3x=8-5

5x=3

x=\(\frac{3}{5}\)

\(\left|x+1\right|+\left|x-5\right|=7.\)

\(Th1:x+1< 0;x-5< 0\)

\(x< -1;x< 5\Rightarrow x< -1\)

\(\left|x+1\right|+\left|x-5\right|=7\)

\(-\left(x+1\right)-\left(x-5\right)=7\)

\(-x-1-x+5=7\)

\(-2x+4=7\)

\(-2x=3\)

\(x=-1,5\left(tm\right)\)

\(Th2:x+1>0;x-5>0\)

\(x>-1;x>5\Rightarrow x>5\)

\(\left|x+1\right|+\left|x-5\right|=7\)

\(x+1+x-5=7\)

\(2x-4=7\)

\(2x=11\)

\(x=5,5\)\(\left(tm\right)\)

\(Th3:x+1\le0;x-5>0\)

\(x\le-1;x>5\)(không xảy ra)

\(Th4:x+1>0;x-5\le0\)

\(x>-1;x\le5\Rightarrow-1< x\le5\)

\(\left|x+1\right|+\left|x-5\right|=7\)

\(-\left(x+1\right)+x-5=7\)

\(-x-1+x-5=7\)( không xảy ra) 

Vậy  x = -1,5 hoặc x = 5,5

\(\)

\(\left|2x+5\right|=3x-8.\)

\(Th1:\)

\(2x+5=-\left(3x-8\right)\)

\(2x+5=-3x+8\)

\(2x+3x=8-5\)

\(5x=3\)

\(x=\frac{3}{5}\)

\(Th2:\)

\(2x+5=3x-8\)

\(2x-3x=-8-5\)

\(-x=-13\)

\(x=13\)

Vậy x = 13 hoặc x = \(\frac{3}{5}\)

Có 2015 số hạng

Tổng là (2x+1+2x+2015).2015:2=0

4x+2016=0

4x=-2016

x=-504

Ủng hộ mk nha

( 2x + 1 ) + ( 2x + 2 ) + ... + ( 2x + 2015 ) = 0

=> ( 2x + 2x + .. + 2x ) + ( 1 + 2 + ... + 2015 ) = 0

           2015 số 2x

=> 2x . 2015 + 2031120 = 0

=> 2x . 2015 = 0 - 2031120

=> 2x . 2015 = - 2031120

=> 2x = ( - 2031120 ) : 2015

=> 2x = - 1008

=> x = ( - 1008 ) : 2

=> x = - 504

=> ( 2x + 2x + .... + 2x + 2x ) + ( 1 + 2 + 3 + .... + 2015 ) = 0

=> ( 2x.2015 ) + { [ 2015.( 2015 + 1 ] : 2 } = 0

=> 4030x + [ ( 2015 . 2016 ) : 2 ] = 0

=> 4030x + ( 4062240 : 2 ) = 0

=> 4030x + 2031120 = 0

=> 4030x = - 2031120

=> x = - 2031120 : 4030 = - 504

Vậy x = - 504