a) x= chịu

b) x=2

Trình bày cách giải ra >:(

=>x+2=4

hay x=2

3x.3² = 81

3x . 9 = 81

3x      = 81 : 9

3x      = 9

 x      = 9:3

 x     = 3

\(\Leftrightarrow3^x=27\)

hay x=3

\(\Leftrightarrow3^x+3^x.3^2=270\Leftrightarrow3^x.10=270\\\Leftrightarrow3^x=3^3\Leftrightarrow x=3\)

     3x - 4 \(⋮\) 3 - x

\(\Rightarrow\) 3x - 4 + 3 . (3 - x) \(⋮\) 3 - x

\(\Rightarrow\) 5 \(⋮\) 3 - x

\(\Rightarrow\) 3 - x \(\in\) Ư(5) = {1 ; - 1 ; 5 ; - 5}

\(\Rightarrow\) x \(\in\) {2 ; 4 ; - 2 ; 8}

Lời giải:

a. 

ƯCLN $ =5^2=25$
BCNN $=3.5^2.7=525$

b.

ƯCLN $=3$

BCLNN $=2^2.3^2.5.7.11=13860$

\(a,0,5x-\frac{2}{3}x=\frac{7}{12}\Rightarrow\frac{1}{2}x-\frac{2}{3}x=\frac{7}{12}\)

\(\Rightarrow x\left(\frac{1}{2}-\frac{2}{3}\right)=\frac{7}{12}\Rightarrow x\cdot\left(\frac{3}{6}-\frac{4}{6}\right)=\frac{7}{12}\)

\(\Rightarrow x\cdot\left(-1\right)=\frac{7}{12}\Rightarrow x=\frac{7}{12}:\left(-1\right)=\frac{7}{-12}\)

\(c,\frac{\left(x-5\right)}{12}\cdot\frac{9}{29}=\frac{-6}{29}\Rightarrow\frac{\left(x-5\right)}{12}=\frac{-6}{29}:\frac{9}{26}\)

\(\frac{\Rightarrow\left(x-5\right)}{12}=\frac{-6}{9}=\frac{-2}{3}\Rightarrow x-5=-\frac{2}{3}\cdot12\)

\(\Rightarrow x-5=\frac{-24}{3}=-8\Rightarrow x=-8+5=-3\)

\(a,0,5x-\frac{2}{3}x=\frac{7}{12}\)

\(\Rightarrow\frac{1}{2}x-\frac{2}{3}x=\frac{7}{12}\)

\(\Rightarrow-\frac{1}{6}x=\frac{7}{12}\)

\(\Rightarrow x=-\frac{7}{2}\)

\(c,\frac{x-5}{12}\cdot\frac{9}{29}=-\frac{6}{29}\)

\(\Rightarrow\frac{x-5}{12}=-\frac{2}{3}\)

\(\Rightarrow x-5=12.\left(-\frac{2}{3}\right)\)

\(\Rightarrow x-5=-8\)

\(\Rightarrow x=-3\)

câu 1 = 001

cầu 2= 77

câu 3= 8256

= [(-125).(-8)].[(-4).25].3

= 1000. (-100).3

= (-100000).3

= -300000

-300000tickticktick nha!!!

| 3x+1|-17=-12

| 3x+1|=-12+17

|3x+1|=5

=>3x+1 thuộc {5;-5}

=>3x thuộc {4;-6}

Do 3x chia hết cho 3 nên 3x=-6

x=-6:3=-2

Vậy x=-2