a) \(\left(2x-3\right)\left(6-2x\right)=0\)

\(\circledast\)TH₁: \(2x-3=0\\ 2x=0+3\\ 2x=3\\ x=\dfrac{3}{2}\)

\(\circledast\)TH₂: \(6-2x=0\\ 2x=6-0\\ 2x=6\\ x=\dfrac{6}{2}=3\)

Vậy \(x\in\left\{\dfrac{3}{2};3\right\}\).

b) \(\dfrac{1}{3}x+\dfrac{2}{5}\left(x-1\right)=0\)

\(\dfrac{1}{3}x=0-\dfrac{2}{5}\left(x-1\right)\)

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

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

\(-\dfrac{11}{15}=-x\left(x-1\right)\)

\(\Rightarrow x=1.491631652\)

Vậy \(x=1.491631652\)

c) \(\left(3x-1\right)\left(-\dfrac{1}{2}x+5\right)=0\)

\(\circledast\)TH₁: \(3x-1=0\\ 3x=0+1\\ 3x=1\\ x=\dfrac{1}{3}\)

\(\circledast\)TH₂: \(-\dfrac{1}{2}x+5=0\\ -\dfrac{1}{2}x=0-5\\ -\dfrac{1}{2}x=-5\\ x=-5:-\dfrac{1}{2}\\ x=10\)

Vậy \(x\in\left\{\dfrac{1}{3};10\right\}\).

d) \(\dfrac{x}{5}=\dfrac{2}{3}\\ x=\dfrac{5\cdot2}{3}\\ x=\dfrac{10}{3}\)

Vậy \(x=\dfrac{10}{3}\).

e) \(\dfrac{x}{3}-\dfrac{1}{2}=\dfrac{1}{5}\\ \)

\(\dfrac{x}{3}=\dfrac{1}{5}+\dfrac{1}{2}\)

\(\dfrac{x}{3}=\dfrac{7}{10}\)

\(x=\dfrac{3\cdot7}{10}\)

\(x=\dfrac{21}{10}\)

Vậy \(x=\dfrac{21}{10}\).

f) \(\dfrac{x}{5}-\dfrac{1}{2}=\dfrac{6}{10}\)

\(\dfrac{x}{5}=\dfrac{6}{10}+\dfrac{1}{2}\)

\(\dfrac{x}{5}=\dfrac{11}{10}\)

\(x=\dfrac{5\cdot11}{10}\)

\(x=\dfrac{55}{10}=\dfrac{11}{2}\)

Vậy \(x=\dfrac{11}{2}\).

g) \(\dfrac{x+3}{15}=\dfrac{1}{3}\\ x+3=\dfrac{15}{3}=5\\ x=5-3\\ x=2\)

Vậy \(x=2\).

h) \(\dfrac{x-12}{4}=\dfrac{1}{2}\\ x-12=\dfrac{4}{2}=2\\ x=2+12\\ x=14\)

Vậy \(x=14\).

khó quá

a. Vì \(\left|x-y-5\right|\ge0\forall x;y;2019\left|y-3\right|^{2020}\ge0\forall y\)

\(\Rightarrow\left|x-y-5\right|+2019\left|y-3\right|^{2020}\ge0\)

Dấu "=" xảy ra \(\Leftrightarrow\orbr{\begin{cases}\left|x-y-5\right|=0\\2019\left|y-3\right|^{2020}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x-y-5=0\\y-3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x-y=5\\y=3\end{cases}}\)

b. \(2\left(x-5\right)^4\ge0\forall x;5\left|2y-7\right|^5\ge0\forall y\)

\(\Rightarrow2\left(x-5\right)^4+5\left|2y-7\right|^5\ge0\)

Dấu "=" xảy ra \(\Leftrightarrow\orbr{\begin{cases}2\left(x-5\right)^4=0\\5\left|2y-7\right|^5=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x-5=0\\2y-7=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=5\\y=\frac{7}{2}\end{cases}}\)

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

\(\Rightarrow-5x-1-\frac{1}{2}x+\frac{1}{3}=\frac{3}{2}x-\frac{5}{6}\)

\(\Rightarrow-5x-\frac{1}{2}x-\frac{3}{2}x=\frac{-5}{6}-\frac{1}{3}+1\)

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

\(\Rightarrow x=\frac{1}{42}\)

Vậy ...

\(\)

\(3.\left(3x-\frac{1}{2}\right)^3+\frac{1}{9}=0\)

\(\Rightarrow3.\left(3x-\frac{1}{2}\right)^3=\frac{-1}{9}\)

\(\Rightarrow\left(3x-\frac{1}{2}\right)^3=\frac{-1}{27}\)

\(\Rightarrow\left(3x-\frac{1}{2}\right)^3=\left(\frac{-1}{3}\right)^3\)

\(\Rightarrow3x-\frac{1}{2}=\frac{-1}{3}\)

\(\Rightarrow3x=\frac{1}{6}\)

\(\Rightarrow x=\frac{1}{18}\)

Vậy...

c: \(\left|\dfrac{7}{5}x+\dfrac{2}{3}\right|=\left|\dfrac{4}{3}x-\dfrac{1}{4}\right|\)

=>7/5x+2/3=4/3x-1/4 hoặc 7/5x+2/3=1/4-4/3x

=>1/15x=-11/12 hoặc 41/15x=-5/12

=>x=-55/4 hoặc x=-25/164

d: |7/8x+5/6|=|1/2x+5|

=>|42x+40|=|24x+240|

=>42x+40=24x+240 hoặc 42x+40=-24x-240

=>18x=200 hoặc 66x=-280

=>x=100/9 hoặc x=-140/33

Việt Nam đất nước anh hùng.....^^ 
Trung Quốc là nước nửa khùng nửa điên. 
Việt Nam đang sống bình yên. 
Trung Quốc đừng có làm phiền Việt Nam. 
Trung Quốc đông dân toàn cỏ rác. 
Việt Nam lác đác toàn siêu nhân. 
Việt Nam cưỡi rồng bay trong gió. 
Trung Quốc cưỡi chó sủa:"gâu" "gâu". 
Thái Lan hỏi nó đi đâu. 
Nó cười, nó bảo:" đi hầu Việt Nam

a) \(\frac{9}{20}\)                                                   c) \(\frac{-55}{4}\)                                                                                                                                 

b) \(\frac{116}{75}\)                                                d) \(\frac{-76}{45}\)

đúng hết đấy nhé mình tính kĩ lắm ko sai đâu

       chúc may mắn

1, Ta có :

a . 81 = 3⁴ => 3^x= 3⁴ => x = 4 .

b. 125 = 5³ => 5^x+2 = 5³ =>x + 2 = 3 => x = 1

c. 2³ * 2^{x - 1} = 64

=> 2^{3 + ( x - 1 )} = 64 = 2⁶ 

^{=>  3 + ( x - 1 ) = 6} 

^{=>           x - 1   = 6 - 3 = 3}

                      ^{x  = 3 + 1}

                       ^{x  = 4}

219 - 7 . ( x+1) = 100

7 . ( x + 1 ) = 219 - 100 = 119

x+ 1= 119:7= 17

x = 17-1=16

(3x - 6 ). 3¹⁰⁰ = 3¹⁰³ 2018^x-3 = 2018

3x - 6 = 3¹⁰³ : 3¹⁰⁰ 2018^x-3 = 2018¹

3x - 6 = 3³ =27 Do x-3=1 cho nên suy ra x=4

3x = 27 + 6

3x = 33

x = 33:3

x = 11

a) 1/3x + 2/5x - 2/5 = 0

=> x = 0,54

b) 12n - 4n^2 - 18 + 6n +0

<=> -4n^2 + 6n - 18 = 0

<=> (-4n)^2 + 6n + 12n - 18 +0

<=> - 2n (2n-3 ) + 6 ( 2n - 3 ) = 0

,<=> ( 6 - 2n ) ( 2n -3 )=0

<=> 6 - 2n = 0 => n +3 / 2n-3 =0 => n = 3/2