10)   \(\frac{x+14}{86}+\frac{x+15}{85}+\frac{x+16}{84}+\frac{x+17}{83}+\frac{x+116}{4}=0\)

\(\Leftrightarrow\)\(\frac{x+14}{86}+1+\frac{x+15}{85}+1+\frac{x+16}{84}+1+\frac{x+17}{83}+1+\frac{x+116}{4}-4=0\)

\(\Leftrightarrow\)\(\frac{x+100}{86}+\frac{x+100}{85}+\frac{x+100}{84}+\frac{x+100}{83}+\frac{x+100}{4}=0\)

\(\Leftrightarrow\)\(\left(x+100\right)\left(\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{4}\right)=0\)

\(\Leftrightarrow\)\(x+100=0\)   (vì  1/86 + 1/85 + 1/84 + 1/83 + 1/4  \(\ne\)0)

\(\Leftrightarrow\)\(x=-100\)

Vậy....

12 mình chịu

11/15 + 8/5=                   Tính phân số

6/7 - 5/21=

25/4 x 16/100

7 x 2/49 =

4/3 : 2/9

5/8 : 25 =

đây là kết quả của mình nhé .

7)    \(\frac{x+25}{75}+\frac{x+30}{70}=\frac{x+35}{65}+\frac{x+40}{60}\)

\(\Leftrightarrow\)\(\frac{x+25}{75}+1+\frac{x+30}{70}+1=\frac{x+36}{65}+1+\frac{x+40}{60}+1\)

\(\Leftrightarrow\)\(\frac{x+100}{75}+\frac{x+100}{70}=\frac{x+100}{65}+\frac{x+100}{60}\)

\(\Leftrightarrow\)\(\left(x+100\right)\left(\frac{1}{75}+\frac{1}{70}-\frac{1}{65}-\frac{1}{60}\right)=0\)

\(\Leftrightarrow\)\(x+100=0\)            (vì 1/75 + 1/70 - 1/65 - 1/60  \(\ne\)0)

\(\Leftrightarrow\)\(x=-100\)

Vậy.....

7)    \(\frac{x+25}{75}+\frac{x+30}{70}=\frac{x+35}{65}+\frac{x+40}{60}\)

\(\Leftrightarrow\)\(\frac{x+25}{75}+1+\frac{x+30}{70}+1=\frac{x+35}{65}+1+\frac{x+40}{60}+1\)

\(\Leftrightarrow\)\(\frac{x+100}{75}+\frac{x+100}{70}=\frac{x+100}{65}+\frac{x+100}{60}\)

\(\Leftrightarrow\)\(\left(x+100\right)\left(\frac{1}{75}+\frac{1}{70}-\frac{1}{65}-\frac{1}{60}\right)=0\)

\(\Leftrightarrow\)\(x+100=0\)    (1/75 + 1/70 - 1/65 - 1/60 \(\ne\)0)

\(\Leftrightarrow\)\(x=-100\)

Vậy...

\(=\dfrac{32}{21}\cdot\dfrac{22}{16}\cdot\dfrac{49}{45}\cdot\dfrac{5}{11}\)

\(=\dfrac{32}{16}\cdot\dfrac{22}{21}\cdot\dfrac{5}{11}\cdot\dfrac{49}{45}\)

\(=2\cdot\dfrac{49}{45}\cdot\dfrac{22}{11}\cdot\dfrac{5}{21}\)

\(=4\cdot\dfrac{49}{21}\cdot\dfrac{5}{45}=4\cdot\dfrac{1}{9}\cdot\dfrac{7}{3}=\dfrac{28}{27}\)

https://hoc24.vn/cau-hoi/a-929-135-569-b-587-319-307c-23-13-x-94-1312d-418-74-115e-47819-54-66819-54f-3221-x-4945-1622-x-1533g-2020x20189-2019x2020-2011giup-minh-voi-m.8283379351991

bn đừng đăng lại câu hỏi đã có ctrl nhé.

\(\dfrac{32}{21}\times\dfrac{49}{45}:\dfrac{16}{22}\times\dfrac{15}{33}\)

\(=\dfrac{32}{21}\times\dfrac{49}{35}\times\dfrac{22}{16}\times\dfrac{15}{33}\)

\(=\dfrac{2\times16\times7\times7\times2\times11\times3\times5}{3\times7\times5\times7\times16\times3\times11}\)

\(=\dfrac{2\times2}{3}\)

\(=\dfrac{4}{3}\)

9: \(\dfrac{x-49}{50}+\dfrac{x-50}{49}=\dfrac{49}{x-50}+\dfrac{50}{x-49}\)

=>x-99=0

hay x=99

7: \(\Leftrightarrow\left(\dfrac{x+25}{75}+1\right)+\left(\dfrac{x+30}{70}+1\right)=\left(\dfrac{x+35}{65}+1\right)+\left(\dfrac{x+40}{60}+1\right)\)

=>x+100=0

hay x=-100

8:

Sửa đề: \(\dfrac{99-x}{101}+\dfrac{97-x}{103}+\dfrac{95-x}{105}+\dfrac{93-x}{107}=-4\) 

\(\Leftrightarrow\left(\dfrac{99-x}{101}+1\right)+\left(\dfrac{97-x}{103}+1\right)+\left(\dfrac{95-x}{105}+1\right)+\left(\dfrac{93-x}{107}+1\right)=0\)

=>200-x=0

hay x=200

bang 0 het nhetk cho minh di

a)    \(\frac{x+14}{86}+\frac{x+15}{85}+\frac{x+16}{84}+\frac{x+17}{83}+\frac{x+116}{4}=0\)

\(\Leftrightarrow\)\(\frac{x+14}{86}+1+\frac{x+15}{85}+1+\frac{x+16}{84}+1+\frac{x+17}{83}+1+\frac{x+116}{4}-4=0\)

\(\Leftrightarrow\)\(\frac{x+100}{86}+\frac{x+100}{85}+\frac{x+100}{84}+\frac{x+100}{83}+\frac{x+100}{4}=0\)

\(\Leftrightarrow\)\(\left(x+100\right)\left(\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{4}\right)=0\)

\(\Leftrightarrow\)\(x+100=0\)

\(\Leftrightarrow\)\(x=-100\)

Vậy...

câu 1:=\(\frac{x+14}{86}+1+\frac{x+15}{85}+1+\frac{x+16}{84}+1+\frac{x+17}{83}+1+\frac{x+116}{4}-4=0\)

=\(\frac{x+100}{86}+\frac{x+100}{85}+\frac{x+100}{84}+\frac{x+100}{83}+\frac{x+100}{4}=0\)

=\(^{(x+100).(\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{4})=0}\)

=\(\orbr{\begin{cases}100+x=0\\\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{4}=0\left(voly\right)\end{cases}}\Leftrightarrow100+x=0\Leftrightarrow x=-100\)

a) `123 - 27 + 27 + 13 - 123`

`= (123 - 123) + (27 - 27) + 13`

`= 0 + 0 + 13`

`= 13`

`---`

b) `175 + 25 + 13 + 15 - 175 - 25`

`= (175-175)+(25-25)+25+13`

`=0+0+25+13`

`=28`

`---`

c) \(53\times39+47\times39+53\times21+47\times21\)

\(=\text{[}\left(53+47\right)\times39]+\left[\left(53+47\right)\times21\right]\)

\(=\left(100\times39\right)+\left(100\times21\right)\)

\(=3900+2100\)

`=6000`

`---`

d) \(49\times35+49\times16-49\times61\)

`=` \(49\times\left(35+16-61\right)\)

`=` \(49\times\left(-10\right)\)

`=-490`