Bn viết lại đề bài rõ hơn được ko?

6\85/7

x phần 15 = 4 phần 10

\(3\left(x-\frac{1}{2}\right)-5\left(x+\frac{3}{5}\right)=-x+\frac{1}{5}\)

\(\Rightarrow3x-\frac{3}{2}-5x-3=-x+\frac{1}{5}\)

\(\Rightarrow3x-5x+x=\frac{1}{5}+\frac{3}{2}+3\)

\(\Rightarrow-x=\frac{17}{10}+3\)

\(\Rightarrow-x=\frac{47}{10}\)

\(\Rightarrow x=-\frac{47}{10}\)

a: \(\frac23=\frac{x}{54}\)

=>\(\frac{x}{54}=\frac{2\cdot18}{3\cdot18}=\frac{36}{54}\)

=>x=36

b: \(\frac{10}{x}=\frac{15}{6}\)

=>\(\frac{10}{x}=\frac52\)

=>\(x=10\times\frac25=\frac{20}{5}=4\)

c: \(\frac23<\frac{x}{6}<1\)

=>\(\frac46<\frac{x}{6}<\frac66\)

=>4<x<6

mà x là số tự nhiên

nên x=5

d: Ta có: \(1<\frac{6}{x}<2\)

=>\(\frac66<\frac{6}{x}<\frac63\)

=>6>x>3

mà x là số tự nhiên

nên x∈{4;5}

bn viết tke bố tôi cx ko hiểu đc

a) \(\frac{2}{3x}=\frac{5}{2}\Leftrightarrow3x=\frac{4}{5}\Rightarrow x=\frac{4}{15}\)

b) \(\frac{x-3}{4}=\frac{1}{2}\Rightarrow x-3=2\Rightarrow x=5\)

c) \(\frac{5}{24+x}=\frac{7}{12}\Rightarrow24+x=\frac{60}{7}\Rightarrow x=\frac{-108}{7}\)

d) \(-6x=18\Rightarrow x=-3\)

\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x.(x+1)}=\frac{2007}{2009}\)

=> \(2.\left(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{x.\left(x+1\right)}\right)=\frac{2017}{2019}\)

=> \(2.\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x.\left(x+1\right)}\right)=\frac{2017}{2019}\)

=> \(2.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{x}-\frac{1}{x+1}\right)=\frac{2017}{2019}\)

=> \(2.\left(\frac{1}{2}-\frac{1}{x+1}\right)=\frac{2007}{2009}\)

=> \(\frac{1}{2}-\frac{1}{x+1}=\frac{2007}{2009}:2\)

=> \(\frac{1}{2}-\frac{1}{x+1}=\frac{2007}{4018}\)

=> \(\frac{1}{x+1}=\frac{1}{2}-\frac{2017}{4018}\)

=> \(\frac{1}{x+1}=\frac{1}{2019}\)

Vì 1 = 1

=> x + 1 = 2019

=> x       = 2019 - 1

=> x       = 2018

tra

r lời 

x=2018 

chúc bn 

hc tốt