duyệt cho mình nhé...thanks

             (x-1)+(x-2)+...+(x-20)=-610

       => (x+x+x+x+...+x)- (1+2+3+4+...+20)=-610

           => 20x-210=-610

                       20x=-610+210

                         20x=-400

                            x=-400:20

                             x=-20   

( x-1)+(x-2)+....+ (x-19)+(x-20)=610.

=>(x+x+x+...x)+(1+2+3+...+20)=610

=>        20x     +          210        = 610

=>       20x                                =610-210

=>       20x                               =400 

=>          x                                =400:20

=>         x                                 = 20

bằng 41

bằng 41 nha bn

Chị gái xinh đẹp à. Câu hỏi của chị khó quá ko ai trả lời. Thôi thì.......k cho mem đi😉

\(x+11\)\(⋮\)\(x+2\)

<=>   \(x+2+9\)\(⋮\)\(x+2\)

mà  \(x+2\)\(⋮\)\(x+2\)

=>  \(9\)\(⋮\)\(x+2\)

hay  \(x+2\)\(\inƯ\left(9\right)\)

đến đây tự lm tiếp

\(a,\Leftrightarrow x=7-4=3\\ b,\Leftrightarrow2x=-18+5=-13\\ \Leftrightarrow x=-\dfrac{13}{2}\\ c,\Leftrightarrow x-21=10\\ \Leftrightarrow x=31\\ d,\Leftrightarrow-12-x+19=0\\ \Leftrightarrow7-x=0\\ \Leftrightarrow x=7\)

a, <=> x=7-4

<=> x=3

b, 2x= -18 +5

<=>2x=-13

<=> x= -13/2

c, <=> x -21=-10

<=> x= -10 +21

<=> x=11

d, <=> -12+19 -x=0

<=> 7-x=0

<=> x=7

\(x=\dfrac{5}{a-1}< 0\)

\(\Leftrightarrow a-1< 0\Leftrightarrow a< 1\left(1\right)\)

Và \(x=\dfrac{5}{a-1}\in Z\)

\(\Rightarrow a-1\inƯ\left(5\right)=\left\{1;-1;5;-5\right\}\left(2\right)\)

\(\Rightarrow a\left\{2;0;6;-4\right\}\)

\(\left(1\right),\left(2\right)\Rightarrow a\in\left\{-4;0\right\}\)

x - 4/5 = 3/7

x = 3/7 + 4/5

x = 43/35

x + 3/7 = 4/5

x = 4/5 - 3/7

x = 13/35

19/20 - x = 8/5 - 3/4

19/20 - x =  17/20

x = 19/20 - 17/20

x = 2/20 = 1/10

4/5 x X = 6/9 - 4/7

4/5 x X = 2/21

x = 2/21 : 4/5

x =5/42

x : 7/9 = 6/8

x = 6/8 x 7/9

x = 7/12

2/3 - x/6 = 6/18

x/6 = 2/3 - 6/18

x/6 = 1/3

x/6 = 2/6

=> x =2

1. x = 43/35

2. x = 13/35

3. x = 1/10

còn lại tự tính nhá

tui bận òi

`a)25/(x+1)-1 1/6=-1/3-0,5`

`=>25/(x+1)=-1/3-1/2+1+1/6`

`=>25/(x+1)=1/3`

`=>75=x+1`

`=>x=74`

Vậy `x=74`

`b)(2x+25 3/5)^2-9/25=0`

`=>(2x+128/5)=9/25`

`**2x+128/5=3/5`

`=>2x=-125/5=-25`

`=>x=-25/2`

`**2x+128/5=-3/5`

`=>2x=-131/5`

`=>x=-131/10`

Giải:

a) \(\dfrac{25}{x+1}-1\dfrac{1}{6}=\dfrac{-1}{3}-0,5\) 

              \(\dfrac{25}{x+1}=\dfrac{-5}{6}+\dfrac{7}{6}\) 

              \(\dfrac{25}{x+1}=\dfrac{1}{3}\) 

\(\Rightarrow1.\left(x+1\right)=25.3\)  

\(\Rightarrow x+1=75\) 

\(\Rightarrow x=75-1\) 

\(\Rightarrow x=74\) 

b) \(\left(2x+25\dfrac{3}{5}\right)^2-\dfrac{9}{25}=0\) 

              \(\left(2x+\dfrac{128}{5}\right)^2=0+\dfrac{9}{25}\) 

             \(\left(2x+\dfrac{128}{5}\right)^2=\dfrac{9}{25}\) 

\(\Rightarrow\left[{}\begin{matrix}\left(2x+\dfrac{128}{5}\right)^2=\left(\dfrac{3}{5}\right)^2\\\left(2x+\dfrac{128}{5}\right)^2=\left(\dfrac{-3}{5}\right)^2\end{matrix}\right.\) 

\(\Rightarrow\left[{}\begin{matrix}2x+\dfrac{128}{5}=\dfrac{3}{5}\\2x+\dfrac{128}{5}=\dfrac{-3}{5}\end{matrix}\right.\) 

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{-25}{2}\\x=\dfrac{-131}{10}\end{matrix}\right.\) 

Chúc bạn học tốt!

a) \(x:\frac{1}{2}+\frac{3}{4}=1\frac{19}{20}\)

   \(x:\frac{1}{2}+\frac{3}{4}=\frac{39}{20}\)

\(x:\frac{1}{2}=\frac{39}{20}-\frac{3}{4}\)

\(x:\frac{1}{2}=\frac{39}{20}-\frac{15}{20}\)

\(x:\frac{1}{2}=\frac{24}{20}\)

\(x=\frac{24}{20}.\frac{1}{2}\)

\(x=\frac{3}{5}\)

\(x:\frac{1}{2}+\frac{3}{4}=1\frac{19}{20}\)

\(x:\frac{1}{2}=1\frac{19}{20}-\frac{3}{4}\)

\(x:\frac{1}{2}=\frac{39}{20}-\frac{3}{4}\)

\(x:\frac{1}{2}=\frac{39}{20}-\frac{15}{20}\)

\(x:\frac{1}{2}=\frac{24}{20}\)

\(x=\frac{24}{20}\times\frac{1}{2}\)

\(x=\frac{24}{40}\)

\(x=\frac{3}{5}\)