Tìm x. ( giúp mình với, ra lâu rồi không ai làm 
)
e) \(\dfrac{-2}{3}-\dfrac{1}{3}\left(2x-5\right)=\dfrac{3}{2}\)
g) \(\dfrac{2}{5}.x+\dfrac{1}{2}=\dfrac{-3}{4}\)
h) \(\left(2x-2\dfrac{4}{5}\right):3\dfrac{1}{8}=1\dfrac{3}{5}\)
i) \(3,2x-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):3\dfrac{2}{3}=\dfrac{7}{20}\)
k)\(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)
Làm giúp mình với, mình hứa tick cho!~
ừ Vy Nguyễn, mik làm nè:
e, \(\dfrac{-2}{3}-\dfrac{1}{3}\left(2x-5\right)=\dfrac{3}{2}.\)
\(\dfrac{1}{3}\left(2x-5\right)=\dfrac{-2}{3}-\dfrac{3}{2}.\)
\(\dfrac{1}{3}\left(2x-5\right)=\dfrac{-4}{6}+\dfrac{-9}{6}.\)
\(\dfrac{1}{3}\left(2x-5\right)=\dfrac{-13}{6}.\)
\(2x-5=\dfrac{-13}{6}:\dfrac{1}{3}.\)
\(2x-5=\dfrac{-13}{6}.3.\)
\(2x-5=\dfrac{-13}{2}.\)
\(2x=\dfrac{-13}{2}+5.\)
\(2x=\dfrac{-13}{2}+\dfrac{10}{2}.\)
\(2x=\dfrac{-3}{2}.\)
\(x=\dfrac{-3}{2}:2.\)
\(x=\dfrac{-3}{2.2}=\dfrac{-3}{4}.\)
g, \(\dfrac{2}{5}x+\dfrac{1}{2}=\dfrac{-3}{4}.\)
\(\dfrac{2}{5}x=\dfrac{-3}{4}-\dfrac{1}{2}.\)
\(\dfrac{2}{5}x=\dfrac{-3}{4}+\dfrac{-2}{4}.\)
\(\dfrac{2}{5}x=\dfrac{-5}{4}.\)
\(x=\dfrac{-5}{4}:\dfrac{2}{5}.\)
\(x=\dfrac{-5}{4}.\dfrac{5}{2}.\)
\(x=\dfrac{-25}{8}.\)
h, \(\left(2x-2\dfrac{4}{5}\right):3\dfrac{1}{8}=1\dfrac{3}{5}.\)
\(\left(2x-2\dfrac{4}{5}\right)=\dfrac{8}{5}.\dfrac{25}{8}.\)
\(\left(2x-2\dfrac{4}{5}\right)=5.\)
\(2x=5+2\dfrac{4}{5}.\)
\(2x=7\dfrac{4}{5}.\)
\(x=7\dfrac{4}{5}:2.\)
\(x=\dfrac{39}{10}.\)
(còn tiếp ở phần sau!!!)
Tiếp:
i, \(3,2x-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):3\dfrac{2}{3}=\dfrac{7}{20}.\)
\(\dfrac{16}{5}x-\left(\dfrac{4}{5}+\dfrac{2}{3}\right)=\dfrac{7}{20}.\dfrac{11}{3}.\)
\(\dfrac{16}{5}x-\left(\dfrac{4}{5}+\dfrac{2}{3}\right)=\dfrac{77}{60}.\)
\(\dfrac{16}{5}x-\left(\dfrac{12}{15}+\dfrac{10}{15}\right)=\dfrac{77}{60}.\)
\(\dfrac{16}{5}x-\dfrac{22}{15}=\dfrac{77}{60}.\)
\(\dfrac{16}{5}x=\dfrac{77}{60}+\dfrac{22}{15}.\)
\(\dfrac{16}{5}x=\dfrac{77}{60}+\dfrac{88}{60}.\)
\(\dfrac{16}{5}x=\dfrac{165}{60}=\dfrac{11}{4}.\)
\(x=\dfrac{11}{4}:\dfrac{16}{5}.\)
\(x=\dfrac{11}{4}.\dfrac{5}{16}=\dfrac{55}{64}.\)
k, \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}.\)
\(\left(\dfrac{3x}{7}+1\right)=\dfrac{-1}{28}.\left(-4\right).\)
\(\left(\dfrac{3x}{7}+1\right)=\dfrac{1}{7}.\)
\(\dfrac{3x}{7}=\dfrac{1}{7}-1.\)
\(\dfrac{3x}{7}=\dfrac{1}{7}-\dfrac{7}{7}.\)
\(\dfrac{3x}{7}=\dfrac{-6}{7}.\)
\(\Rightarrow3x=-6.\)
\(\Rightarrow x=-6:3=-2.\)
~ Chúc bn học tốt!!! ~
Bài mik đúng thì nhớ tik mik nha!!!
a, \(\dfrac{-2}{3}-\dfrac{1}{3}\left(2x-5\right)=\dfrac{3}{2}\)
\(\Rightarrow\dfrac{1}{3}\left(2x-5\right)=\dfrac{-2}{3}+\dfrac{3}{2}\)
\(\Rightarrow\dfrac{1}{3}\left(2x-5\right)=\dfrac{-5}{6}\)
\(\Rightarrow2x-5=\dfrac{-5}{6}.3\)
\(\Rightarrow2x-5=\dfrac{-5}{2}\)
\(\Rightarrow2x=\dfrac{5}{2}\)
\(\Rightarrow x=\dfrac{5}{2}.\dfrac{1}{2}\)
\(\Rightarrow x=\dfrac{5}{4}\)
b, \(\dfrac{2}{5}x+\dfrac{1}{2}=\dfrac{-3}{4}\)
\(\Rightarrow\dfrac{2}{5}x=\dfrac{-3}{4}+\dfrac{1}{2}\)
\(\Rightarrow\dfrac{2}{5}x=\dfrac{-1}{4}\)
\(\Rightarrow x=\dfrac{-1}{4}.\dfrac{5}{2}\)
\(\Rightarrow x=\dfrac{-5}{8}\)
c, \(\left(2x-2\dfrac{4}{5}\right):3\dfrac{1}{8}=1\dfrac{3}{5}\)
\(\Rightarrow\left(2x-\dfrac{14}{5}\right):\dfrac{25}{8}=\dfrac{8}{5}\)
\(\Rightarrow2x-\dfrac{14}{5}=\dfrac{8}{5}.\dfrac{25}{8}\)
\(\Rightarrow2x-\dfrac{14}{5}=5\)
\(\Rightarrow2x=5+\dfrac{14}{5}\)
\(\Rightarrow2x=\dfrac{39}{5}\)
\(\Rightarrow x=\dfrac{39}{5}.\dfrac{1}{2}\)
\(\Rightarrow x=\dfrac{39}{10}\)
d, \(3,2x-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):3\dfrac{2}{3}=\dfrac{7}{20}\)
\(\Rightarrow\dfrac{16}{5}x-\dfrac{22}{15}:\dfrac{11}{3}=\dfrac{7}{20}\)
\(\Rightarrow\dfrac{16}{5}x-\dfrac{3}{5}=\dfrac{7}{20}\)
\(\Rightarrow\dfrac{16}{5}x=\dfrac{7}{20}+\dfrac{3}{5}\)
\(\Rightarrow\dfrac{16}{5}x=\dfrac{19}{20}\)
\(\Rightarrow x=\dfrac{19}{20}.\dfrac{5}{16}\)
\(\Rightarrow x=\dfrac{19}{64}\)
e, \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)
\(\Rightarrow\dfrac{3x}{7}+1=\dfrac{-1}{28}.\left(-4\right)\)
\(\Rightarrow\dfrac{3x}{7}+1=\dfrac{1}{7}\)
\(\Rightarrow\dfrac{3x}{7}=\dfrac{1}{7}-1\)
\(\Rightarrow\dfrac{3x}{7}=\dfrac{-6}{7}\)
\(\Rightarrow3x=-6\)
\(\Rightarrow x=-2\)
