a)

`x/(-8)=5/4`

`=>x*4=5*(-8)`

`=>4x=-40`

`=>x=-40:4`

`=>x=-10`

b)

`(-13)/x=(-65)/10`

`=>(-13)/x=(-13)/2`

`=>x=2`

c)

`(-6)/5=(-12)/x`

`<=>(-12)/10=(-12)/x`

`<=>x=10`

d)

`(x-2)/2=8/(x-2)`

`=>(x-2)(x-2)=8*2`

`=>(x-2)^2=16`

`=>x-2=4` hoặc`x-2=-4`

`=>x=4+2` hoặc `x=-4+2`

`=>x=6` hoặc `x=-2`

`x/(-8) = 5/4`

`=> 4x=5.(-8)`

`=>4x=-40`

`=>x=-40:4`

`=>x=-10`

__

`-13/x =-65/10`

`=> -65x=-130`

`=>x=-130:(-65)`

`=>x= 2`

__

`-6/5 =-12/x`

`=> -6x=-12.5`

`=> -6x= -60`

`=>x=-60:(-6)`

`=>x=10`

__

`(x-2)/2 = 8/(x-2)`

`=>(x-2)^2=2.8`

`=>(x-2)^2=16`

`=> (x-2)^2=+-4^2`

\(\Rightarrow\left[{}\begin{matrix}x-2=4\\x-2=-4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=6\\x=-2\end{matrix}\right.\)

Bài 1 : \(\frac{1}{2}+X.\frac{3}{4}=2\Rightarrow X.\frac{3}{4}=2-\frac{1}{2}=\frac{3}{2}\)

\(\Rightarrow X=\frac{3}{2}:\frac{3}{4}=\frac{3}{2}.\frac{4}{3}=2\)

bài 3: a) =3241+6759+754+1246=10000+2000=12000

b) =9875+125+2141+1859=10000+4000=14000

bài 1 

\(\frac{1}{2}\)+ X x \(\frac{3}{4}=\)2

\(\frac{1}{2}\)+ X = 2 : \(\frac{3}{4}\)

\(\frac{1}{2}\)+ X = \(\frac{8}{3}\)

X = \(\frac{8}{3}\)-- \(\frac{1}{2}\)

X=\(\frac{13}{6}\)

bài 2 

https://olm.vn/hoi-dap/question/540195.html

\(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+\left(x+4\right)+\left(x+5\right)=65\)

<=>  \(5x+15=65\)

<=> \(5x=50\)

<=> \(x=10\)

Vậy...

p/s: chúc bạn học tốt

`a)(x-2)(x^2+2x+4)-x(x-3)(x+3)=26`

`<=>x^3-2^3-x(x^2-9)=26`

`<=>x^3-8-x^3+9x=26`

`<=>9x-8=26`

`<=>9x=34`

`<=>x=34/9`

`b)(x-3)(x^2+3x+9)-x(x+4)(x-4)=21`

`<=>x^3-3^3-x(x^2-16)=21`

`<=>x^3-27-x^3+16x=21`

`<=>16x-27=21`

`<=>16x=48`

`<=>x=3`

5x+(1+2+3+4+5)=65

5x+15=65

5x=50

x=10

5x+1+2+3+4+5=65

=>5x+15=65

=>5x=50

=>x=10

\(5x+\frac{5.6}{2}=65\Rightarrow x=\frac{65-15}{5}=10\)

`a,`\(2^x -15= 2^4+1\)

`-> 2^x-15=17`

`-> 2^x=17+15`

`-> 2^x=32`

`-> 2^x=2^5`

`-> x=5`

`b,` Có phải đề là \(\dfrac{x+1}{65}+\dfrac{x+2}{64}=\dfrac{x+3}{63}+\dfrac{x+4}{62}\) ?

`=>`\(\dfrac{x+1}{65}+1+\dfrac{x+2}{64}+1=\dfrac{x+3}{63}+1+\dfrac{x+4}{62}+1\)

`=>`\(\dfrac{x+1+65}{65}+\dfrac{x+2+64}{64}-\dfrac{x+3+63}{63}-\dfrac{x+4+62}{62}=0\)

`=>`\(\dfrac{x+66}{65}+\dfrac{x+66}{64}-\dfrac{x+66}{63}-\dfrac{x+66}{62}=0\)

`=>`\(\left(x+66\right)\left(\dfrac{1}{65}+\dfrac{1}{64}-\dfrac{1}{63}-\dfrac{1}{62}\right)=0\)

Mà `1/65+1/64-1/63-1/62 \ne 0`

`-> x+66=0`

`-> x=-66`

a: =>2^x=2^4+16=32

=>x=5

b: Sửa đề: \(\dfrac{x+1}{65}+\dfrac{x+2}{64}=\dfrac{x+3}{63}+\dfrac{x+4}{62}\)

=>\(\left(\dfrac{x+1}{65}+1\right)+\left(\dfrac{x+2}{64}+1\right)=\left(\dfrac{x+3}{63}+1\right)+\left(\dfrac{x+4}{62}+1\right)\)

=>x+66=0

=>x=-66

a) \(75:\left(x-2\right)+4=7\)

\(\Rightarrow75:\left(x-2\right)=7-4\)

\(\Rightarrow75:\left(x-2\right)=3\)

\(\Rightarrow x-2=75:3\)

\(\Rightarrow x-2=25\)

\(\Rightarrow x=27\)

b) \(125-3\left(x+3\right)=65\)

\(\Rightarrow3\left(x+3\right)=125-65\)

\(\Rightarrow3\left(x+3\right)=60\)

\(\Rightarrow x+3=60:3\)

\(\Rightarrow x+3=20\)

\(\Rightarrow x=17\)

a,\(75:\left(x-2\right)+4=7\\ \Rightarrow75:\left(x+2\right)=3\\ \Rightarrow x+2=25\\ \Rightarrow x=23.\)

b, \(125-3\left(x+3\right)=65\\ \Rightarrow3\left(x+3\right)=60\\ \Rightarrow x+3=20\\ \Rightarrow x=17.\)

a, x= 27

b, x= 17