Giải:

\(0,28-0,3:\left(50\%x-1\dfrac{1}{3}\right)=-1\dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{7}{25}-\dfrac{3}{10}:\left(\dfrac{1}{2}x-\dfrac{4}{3}\right)=-\dfrac{5}{3}\)

\(\Leftrightarrow\dfrac{3}{10}:\left(\dfrac{1}{2}x-\dfrac{4}{3}\right)=\dfrac{7}{25}-\left(-\dfrac{5}{3}\right)\)

\(\Leftrightarrow\dfrac{3}{10}:\left(\dfrac{1}{2}x-\dfrac{4}{3}\right)=\dfrac{146}{75}\)

\(\Leftrightarrow\dfrac{1}{2}x-\dfrac{4}{3}=\dfrac{3}{10}:\dfrac{146}{75}\)

\(\Leftrightarrow\dfrac{1}{2}x-\dfrac{4}{3}=\dfrac{45}{292}\)

\(\Leftrightarrow\dfrac{1}{2}x=\dfrac{45}{292}-\dfrac{4}{3}\)

\(\Leftrightarrow\dfrac{1}{2}x=-\dfrac{1033}{876}\)

\(\Leftrightarrow x=-\dfrac{1033}{876}:\dfrac{1}{2}\)

\(\Leftrightarrow x=-\dfrac{1033}{438}\)

Vậy \(x=-\dfrac{1033}{438}\).

Chúc bạn học tốt!

\(\dfrac{1}{3}-\left(1\dfrac{1}{2}-x\right)=0,3\\ \dfrac{1}{3}-\left(\dfrac{3}{2}-x\right)=\dfrac{3}{10}\\ \dfrac{3}{2}-x=\dfrac{1}{3}-\dfrac{3}{10}\\ \dfrac{3}{2}-x=\dfrac{1}{30}\\ x=\dfrac{3}{2}-\dfrac{1}{30}=\dfrac{44}{30}\)

16 : (0,3 * x +2,5) : x = 17 + 3= 20

 -> \(\frac{0,3\times x+2,5}{x}=\frac{16}{20}=\frac{4}{5}\)

    \(\frac{0,3\times x}{x}+\frac{2,5}{x}=\frac{4}{5}\)

        \(0,3+\frac{2,5}{x}=\frac{4}{5}\)

                      \(\frac{2,5}{x}=\frac{4}{5}-0,3\)

                      \(\frac{2,5}{x}=\frac{1}{2}\)

                       \(x=2,5:\frac{1}{2}=5\)

Mình thay x là a nha:

16 : (0,3 x a + 2,5) : a - 3 = 17

(16 : 0,3 x 16 :a + 26 : 2,5) : a = 17 + 3

(\(\frac{160}{3}\) x \(\frac{16}{a}\) + \(\frac{52}{5}\)) : a = 20

\(\frac{160}{3}\) : a x \(\frac{16}{a}\) :a + \(\frac{52}{5}:a\)= 20

\(\frac{160}{3a}\times\frac{16}{a\times a}+\frac{52}{5a}=20\)

... 

\(\dfrac{-8}{13}+\dfrac{-7}{17}+\dfrac{21}{13}\le x\le\dfrac{-9}{14}+3+\dfrac{5}{-14}\)

=> \(\dfrac{10}{17}\le x\le2\)

=> \(\dfrac{10}{17}\le\dfrac{17x}{17}\le\dfrac{34}{17}\)

=> 10 \(\le17x\le34\)
=> x = 1; 2 (thỏa mãn)
@Khánh Linh

16 : (0,3 x x +2,5):x-3=17

(0,3 x x +2,5):x-3=16:17=16/17

(0,3 x x +2,5):x=16/17+3=67/17

=>0,3 x x +2,5=67x/17

0,3 x x=67x/17-2,5=67x-42.5/17

=>x=67x-42.5/17:0,3=670x-425/51

=>51x x=670x-425

=>670xx-51xx=425

=>619xx=425

=>x=425:619

Chắc mình sai

0,3 : x + 2,5 : x - 3 = 17

0,3 : x + 2,5 : x = 17 + 3

0,3 : x + 2,5 : x = 20

( 0,3 + 2,5 ) : x = 20

2,8 : x = 20

       x = 2,8 : 20

       x = 0,14

cho mk sửa lại

tacó:

\(\dfrac{-64}{125}=\left(\dfrac{-4}{5}\right)^3\)

suy ra\(\dfrac{2}{3}-\dfrac{3}{5}x=\dfrac{-4}{5}\)

\(\dfrac{3}{5}x=\dfrac{2}{3}-\dfrac{-4}{5}\)

\(\dfrac{3}{5}x=\dfrac{22}{15}\)

\(x=\dfrac{22}{15}:\dfrac{3}{5}\)

\(x=\dfrac{22}{9}\)

ta có:

\(\dfrac{-64}{125}=\left(\dfrac{-16}{5}\right)^3\)

suy ra \(\dfrac{2}{3}-\dfrac{3}{5}x=\dfrac{-16}{5}\)

\(\dfrac{3}{5}x=\dfrac{2}{3}-\dfrac{-16}{5}\)

\(\dfrac{3}{5}x=\dfrac{58}{15}\)

\(x=\dfrac{58}{15}:\dfrac{3}{5}\)

\(x=\dfrac{58}{9}\)

tick cho mk với nha

\(\dfrac{x+1}{2017}+\dfrac{x+2}{2016}=\dfrac{x+3}{2015}-1\)

\(\Leftrightarrow\dfrac{x+1}{2017}+1+\dfrac{x+2}{2016}+1=\dfrac{x+3}{2015}-1+2\)

\(\Leftrightarrow\dfrac{x+100}{2017}+\dfrac{x+100}{2016}=\dfrac{x+100}{2015}\)

\(\Leftrightarrow\dfrac{x+100}{2017}+\dfrac{x+100}{2016}+\dfrac{x+100}{2015}=0\)

\(\Leftrightarrow\left(x+100\right)\left(\dfrac{1}{2017}+\dfrac{1}{2016}+\dfrac{1}{2015}\right)=0\)

Do \(\dfrac{1}{2017}+\dfrac{1}{2016}+\dfrac{1}{2015}\ne0\) nên \(x+100=0\)

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

Vậy \(x=\left(-100\right)\)

(Thêm ở cả 2 vế cùng một số để tạo ra nhân tử chung ở tử (x + 2018))