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26 tháng 4 2019

\(a)\left(3\frac{1}{2}-x\right).1\frac{1}{4}=\frac{15}{6}\)

\(\left(\frac{7}{2}-x\right).\frac{5}{4}=\frac{15}{6}\)

\(\frac{7}{2}-x=\frac{15}{6}:\frac{5}{4}\)

\(\frac{7}{2}-x=2\)

\(x=\frac{7}{2}-2\)

\(\Rightarrow x=\frac{3}{2}\)

26 tháng 4 2019

\(b)\frac{3}{2}-x=-\frac{7}{4}+5x\)

\(\frac{3}{2}-\frac{7}{4}=x+5x\)

\(-\frac{1}{4}=6x\)

\(x=-\frac{1}{4}:6\)

\(\Rightarrow x=-\frac{1}{24}\)

1 tháng 5 2019

a, x-1:4/3+9/16=-5^(^laf mũ)2/4^2

x-1:4/3+9/16=25/16

x-1:4/3=25/16-9/16

x-1:4/3=1

x-1=1.4/3

x-1=4/3

x=4/3+1

x=7/3

kl:...................(hì tự viết nha mik lười viết)

b, 5/2x+2-31/2=1/6

5/2x+2=1/6+31/2

5/2x+2=16

5/2x=16-2

5/2x=14

x=14:5/2

x=28/5(vì 28 ko chia hết cho 5 nên mik viết như vậy)

*chúc bn học tốt nha*         ^-^                        *_*

24 tháng 4 2019

a) \(2.\left(x+\frac{2}{5}\right)+1\frac{1}{4}=\frac{11}{20}\)

\(2.\left(x+\frac{2}{5}\right)+\frac{5}{4}=\frac{11}{20}\)

\(2.\left(x+\frac{2}{5}\right)=\frac{-7}{10}\)

\(x+\frac{2}{5}=\frac{-7}{20}\)

\(x=\frac{-13}{20}\)

Vậy \(x=\frac{-13}{20}\)

24 tháng 4 2019

b)\(x-1\frac{1}{8}-\frac{2}{3}x-\frac{5}{6}x=75\%\)

  \(\left(x-\frac{2}{3}x-\frac{5}{6}x\right)-\frac{9}{8}=\frac{3}{4}\)

\(\frac{-1}{2}x-\frac{9}{8}=\frac{3}{4}\)

\(\frac{-1}{2}x=\frac{15}{8}\)

\(x=\frac{-15}{4}\)

Vậy \(x=\frac{-15}{4}\)

25 tháng 4 2019

\(\frac{4}{5}\)\(\frac{1}{5}\)\(\frac{-2}{15}\)\(\frac{4}{5}\)\(\frac{1}{5}\)\(\frac{-15}{2}\)=\(\frac{4}{5}\) + \(\frac{-3}{2}\)\(\frac{-7}{10}\)

25 tháng 4 2019

b = \(\frac{-7}{12}\). (\(\frac{3}{11}\)\(\frac{-14}{11}\)) + \(\frac{5}{6}\)\(\frac{-7}{12}\). (-1) + \(\frac{5}{6}\)\(\frac{7}{12}\)\(\frac{10}{12}\)\(\frac{17}{12}\)

Giải:

a) \(\dfrac{-5}{8}=\dfrac{x}{16}\) 

\(\Rightarrow x=\dfrac{16.-5}{8}=-10\) 

\(\dfrac{3x}{9}=\dfrac{2}{6}\) 

\(\Rightarrow3x=\dfrac{2.9}{6}=3\) 

\(\Rightarrow x=1\)

b) \(\dfrac{x+3}{15}=\dfrac{1}{3}\)  

\(\Rightarrow x+3=\dfrac{1.15}{3}=5\) 

\(\Rightarrow x=2\)

\(\dfrac{6}{2x+1}=\dfrac{2}{7}\) 

\(\Rightarrow2x+1=\dfrac{6.7}{2}=21\) 

\(\Rightarrow x=10\)

c) \(\dfrac{4}{x-6}=\dfrac{y}{24}=\dfrac{-12}{18}\) 

\(\Rightarrow\dfrac{4}{x-6}=\dfrac{-12}{18}\) 

\(\Rightarrow x-6=\dfrac{18.4}{-12}=-6\) 

\(\Rightarrow x=0\) 

\(\Rightarrow\dfrac{y}{24}=\dfrac{-12}{18}\) 

\(\Rightarrow y=\dfrac{-12.24}{18}=-16\) 

 \(\dfrac{3-x}{-12}=\dfrac{16}{y+1}=\dfrac{192}{-72}\) 

\(\Rightarrow\dfrac{3-x}{-12}=\dfrac{192}{-72}\) 

\(\Rightarrow3-x=\dfrac{192.-12}{-72}=32\) 

\(\Rightarrow x=-29\) 

\(\Rightarrow\dfrac{16}{y+1}=\dfrac{192}{-72}\) 

\(\Rightarrow y+1=\dfrac{16.-72}{192}=-6\) 

d) \(\dfrac{-2}{3}< \dfrac{x}{5}< \dfrac{-1}{6}\) 

\(\Rightarrow\dfrac{-20}{30}< \dfrac{6x}{30}< \dfrac{-5}{30}\) 

\(\Rightarrow6x\in\left\{-18;-12;-6\right\}\) 

\(\Rightarrow x\in\left\{-3;-2;-1\right\}\) 

\(\dfrac{-1}{5}\le\dfrac{x}{8}\le\dfrac{1}{4}\) 

\(\Rightarrow\dfrac{-8}{40}\le\dfrac{5x}{40}\le\dfrac{10}{40}\) 

\(\Rightarrow5x\in\left\{-5;0;5;10\right\}\) 

\(\Rightarrow x\in\left\{-1;0;1;2\right\}\) 

e) \(\dfrac{x+46}{20}=x\dfrac{2}{5}\) 

\(\Rightarrow\dfrac{x+46}{20}=x+\dfrac{2}{5}\) 

\(\Rightarrow\dfrac{x+46}{20}=\dfrac{5x+2}{5}\) 

\(\Rightarrow5.\left(x+46\right)=20.\left(5x+2\right)\) 

\(\Rightarrow5x+230=100x+40\) 

\(\Rightarrow5x-100x=40-230\) 

\(\Rightarrow-95x=-190\) 

\(\Rightarrow x=-190:-95\) 

\(\Rightarrow x=2\) 

\(y\dfrac{5}{y}=\dfrac{86}{y}\) 

\(\Rightarrow y+\dfrac{5}{y}=\dfrac{86}{y}\) 

\(\Rightarrow\dfrac{y^2+5}{y}=\dfrac{86}{y}\) 

\(\Rightarrow y^2+5=86\) 

\(\Rightarrow y^2=86-5\) 

\(\Rightarrow y^2=81\) 

\(\Rightarrow\left[{}\begin{matrix}y=9\\y=-9\end{matrix}\right.\) 

Chúc bạn học tốt!

20 tháng 4 2015

\(\frac{7}{3}:\left(4.x-1\right)^2-\frac{1}{4}=\frac{1}{3}\)

\(\frac{7}{3}:\left(4.x-1\right)^2=\frac{1}{3}+\frac{1}{4}\)

\(\frac{7}{3}:\left(4.x-1\right)^2=\frac{7}{12}\)

\(\left(4.x-1\right)^2=\frac{7}{3}:\frac{7}{12}\)

\(\left(4.x-1\right)^2=4\)

\(\left(4.x-1\right)^2=2^2\)

\(4.x-1=2\)

\(4.x=2+1\)

\(4.x=3\)

\(x=3:4\)

\(x=0,75\)