Bài 2:

a, (-2)3.34 = (-8) . 81 = 648

b,54.(-3)2 =  625 . 9 = 5625

Bài 3:

a, 2x-25=45  <=> 2x = 70  <=> x= 35

Vậy  x= 35

b,3x+17=2  <=> 3x = -15   <=> x = -5

Vậy  x= -5

c,/x/ ≤ 8       <=>    x ≤ 8     hoặc     x ≤ -8

Vậy x ≤ 8  hoặc  x ≤ -8

d,/ x-1/=0     <=>    x - 1 = 0    <=> x = 1

Vậy  x= 1

Bài 2: 

a: =>x=0 hoặc x=-3

b: =>x-2=0 hoặc 5-x=0

=>x=2 hoặc x=5

c: =>x-1=0

hay x=1

\(1.x^2+11x=0\)

\(\Leftrightarrow x\left(x+11\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=0\\x+11=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=0\\x=-11\end{cases}}\)

\(2.\left(x^2-1\right)\left(x^2-9\right)=0\)

\(\Leftrightarrow\left(x+1\right)\left(x-1\right)\left(x+9\right)\left(x-9\right)=0\)

chia thành 4 TH :

\(TH1:X-1=0\)

\(\Leftrightarrow x=1\)

\(TH2:x+1=0\)

\(\Leftrightarrow x=-1\)

\(TH3:X+9=0\)

\(\Leftrightarrow X=-9\)

\(TH4:x-9=0\)

\(\Leftrightarrow x=9\)

Kết luận ....

\(3.\left(\left|x+1\right|-5\right)\left(x^2-9\right)\)

\(\Leftrightarrow\left(\left|x+1\right|-5\right)\left(x-3\right)\left(x+3\right)=0\)

\(\Leftrightarrow\hept{\begin{cases}\left|x+1\right|-5=0\\x-3=0\\x+3=0\end{cases}}\)

\(\Leftrightarrow\hept{\begin{cases}\left|x+1\right|=5\\x=3\\x=-3\end{cases}}\)

\(\Leftrightarrow\hept{\begin{cases}x+1=+_-5\Leftrightarrow x+1=5,x+1=-5\Leftrightarrow x=4,x=-6\\x=3x\\x=-3\end{cases}}\)

kết luận x=.....

\(4.\left(3x-16\right)⋮\left(x+2\right)\)

\(\Leftrightarrow\left(3x+6\right)-22\)

\(\Leftrightarrow3\left(x+2\right)-22⋮\left(x+2\right)\)

Vì\(\left(x+2\right)⋮\left(x+2\right)\)

\(\Rightarrow\left(3x-16\right)⋮\left(x+2\right)\)

Kết luận x=.....

a: \(x+6\dfrac{1}{8}=8\)

=>\(x+\dfrac{49}{8}=\dfrac{64}{8}\)

=>\(x=\dfrac{64}{8}-\dfrac{49}{8}=\dfrac{15}{8}\)

b: \(\dfrac{11}{2}\cdot x=\dfrac{1}{5}:\dfrac{1}{3}\)

=>\(x\cdot\dfrac{11}{2}=\dfrac{1}{5}\cdot3=\dfrac{3}{5}\)

=>\(x=\dfrac{3}{5}:\dfrac{11}{2}=\dfrac{3}{5}\cdot\dfrac{2}{11}=\dfrac{6}{55}\)

c: \(x\cdot\dfrac{3}{5}+\dfrac{2}{5}\cdot x=\dfrac{4}{9}+\dfrac{1}{3}\)

=>\(x\left(\dfrac{3}{5}+\dfrac{2}{5}\right)=\dfrac{4}{9}+\dfrac{3}{9}\)

=>\(x\cdot1=\dfrac{7}{9}\)

=>\(x=\dfrac{7}{9}\)

a: 2/5<>-4/10

b: \(\dfrac{4}{-3}=-\dfrac{8}{6}\left(=-\dfrac{4}{3}\right)\)

c: \(-\dfrac{1}{5}< >-\dfrac{1}{-5}\)

d: \(\dfrac{5}{11}=\dfrac{-5}{-11}\left(=\dfrac{5}{11}\right)\)

\(b,\left(2x+1\right).\left(39-2\right)=-55\)

\(\Rightarrow\left(2x+1\right).37=-55\)

\(\Rightarrow3x+1=-\frac{55}{37}\)

\(\Rightarrow3x=-\frac{92}{37}\)

\(\Rightarrow x=-\frac{92}{111}\)

\(c,\left(x-7\right)\left(x+3\right)< 0\)

\(\Rightarrow\orbr{\begin{cases}x-7>0;x+3< 0\\x-7< 0;x+3>0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x>7;x< -3\\x< 7;x>-3\end{cases}}\)

`a)4/5:3/x xx2/11=24/165`

`(4/5xx2/11)xx 3/x=8/55`

`8/55xx3/x=8/55`

`3/x=8/55:8/55`

`3/x=1`

`3:x=1`

`x=3:1`

`x=3`

____________________________________________

`b)4/3:x/5=5/13xx4/9`

`4/3:x/5=20/117`

`x/5=4/3:20/117`

`x/5=39/5`

`x=39`

A) 4/5:3/x X 2/11=24/165

\(\dfrac{4}{5}:\dfrac{3}{x}X\dfrac{2}{11}=\dfrac{24}{165}\)

\(\dfrac{3}{x}=\dfrac{24}{165}:\dfrac{4}{5}:\dfrac{2}{11}\)

\(\dfrac{3}{x}=1\)

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

=> x=3

B) \(\dfrac{4}{3}:\dfrac{x}{5}=\dfrac{5}{13}x\dfrac{4}{9}\)

\(\dfrac{4}{3}:\dfrac{x}{5}=\dfrac{20}{117}\)

\(\dfrac{x}{5}=\dfrac{4}{3}:\dfrac{20}{117}\)

\(\dfrac{x}{5}=\dfrac{39}{5}\)

=> x = 39

theo cách khác hổng được hả