Bài 1: 

a: x/-2=-18/x

=>x²=36

=>x=6 hoặc x=-6

b: x/2+x/5=17/10

=>7/10x=17/10

hay x=17/7

Bài 1: 

Ta có: \(x-35\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow65\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow x=\dfrac{1}{25}:\dfrac{13}{20}=\dfrac{1}{25}\cdot\dfrac{20}{13}=\dfrac{4}{65}\)

Vậy: \(x=\dfrac{4}{65}\)

Bài 2: 

a) Ta có: \(17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)\)

\(=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)

\(=11+\dfrac{2}{31}-\dfrac{15}{17}\)

\(=\dfrac{5366}{527}\)

x:3/4=13/8

x=13/8.3/4

x=39/32

\(\Rightarrow x:\dfrac{3}{4}=\dfrac{13}{8}\)

\(\Rightarrow x=\dfrac{13}{8}\cdot\dfrac{3}{4}\)

\(\Rightarrow x=\dfrac{39}{32}\)

\(\Leftrightarrow x:\dfrac{3}{4}=\dfrac{13}{8}\)

\(\Leftrightarrow x=\dfrac{13}{8}\times\dfrac{3}{4}\)

\(\Leftrightarrow x=\dfrac{39}{32}\)

\(\frac{5}{8}-\frac{3}{8}.x=\left(-\frac{1}{2}\right)^4+\frac{5}{6}\)

\(\Leftrightarrow\frac{5}{8}-\frac{3}{8}.x=\frac{1}{16}+\frac{5}{6}\)

\(\Leftrightarrow\frac{3}{8}.x=\frac{5}{8}-\left(\frac{1}{16}+\frac{5}{6}\right)\)

\(\Leftrightarrow\frac{3}{8}.x=\frac{5}{8}-\frac{5}{96}\)

\(\Leftrightarrow\frac{3}{8}.x=\frac{55}{96}\)

\(\Leftrightarrow x=\frac{55}{96}:\frac{3}{8}\)

\(\Leftrightarrow x=\frac{55}{36}\)

Vậy : \(x=\frac{55}{36}\)

Chúc bạn học tốt nhé !

xx là sao??? vs lại tìm x hay tinh vậy, mik làm theo cách nghĩ của mik:

\(\frac{\left(x+5\right)^2+\left(x-5\right)^2}{x^2+25}=\frac{x^2+10x+25+x^2-10x+25}{x^2+25}\)

\(=\frac{2x^2+50}{x^2+25}=\frac{2\left(x^2+25\right)}{x^2+25}=2\)

Vậy GTBT .... là 2 vs mọi x 

a, \(x + 1/6 = -3/8 \)

\(x = -3/8 - 1/6\)

\(x = -13/24\)

Vậy \(x = -13/24\)

b, \(-3/7 - x = 4/5 - 2/3\)

\(-3/7 - x = 2/15\)

\(x = -3/7 - 2/15\)

\(x = -59/105.\)

Vậy \(x = -59/105\)

x+1/6=-3/8

x=-3/8-1/6

x=-13/24

-3/7-x=4/5+-2/3
-3/7-x=2/15

x=-3/7-2/15

x=-59/105

tham khảo

`x xx 6/7=5/14`

`=>x=5/14:6/7`

`=>x=5/14xx7/6`

`=>x=35/84`

`=>x=5/12`

Vậy `x=5/12`

__

`x:2/3=4/9`

`=>x=4/9xx2/3`

`=>x=8/27`

Vậy `x=8/27`

__

`x-1/4=3/2`

`=>x=3/2+1/4`

`=>x=6/4+1/4`

`=>x=7/4`

Vậy `x=7/4`

__

`x+4/5=8/9`

`=>x=8/9-4/5`

`=>x=40/45-36/45`

`=>x=4/45`

Vậy `x=4/45`

\(x\cdot\dfrac{6}{7}=\dfrac{5}{14}\)

\(x\)         \(=\dfrac{5}{14}:\dfrac{6}{7}\)

\(x\)           \(=\dfrac{5}{12}\)

\(x:\dfrac{2}{3}=\dfrac{4}{9}\)

\(x\)        \(=\dfrac{4}{9}\cdot\dfrac{2}{3}\)

\(x\)          \(=\dfrac{8}{27}\)

\(x-\dfrac{1}{4}=\dfrac{3}{2}\)

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

\(x\)            \(=\dfrac{7}{4}\)

\(x+\dfrac{4}{5}=\dfrac{8}{9}\)

\(x\)          \(=\dfrac{8}{9}-\dfrac{4}{5}\)

\(x\)            \(=\dfrac{4}{45}\)