x : 1/2 = 1 1/7

=> x= 8/7 . 1/2 nha

phép tính thường 1 1/7 : 1/2 mới là  8/7 . 2/1

Đây là tìm x đảo dấu ban oii^^

\(a,\left|x\right|+\dfrac{1}{2}=3\\ \Rightarrow\left|x\right|=3-\dfrac{1}{2}\\ \Rightarrow\left|x\right|=\dfrac{5}{2}\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=-\dfrac{5}{2}\end{matrix}\right.\)

\(b,10,23-\left|x\right|=5\\ \Rightarrow\left|x\right|=10,23-5\\ \Rightarrow\left|x\right|=5,23\\ \Rightarrow\left[{}\begin{matrix}x=5,23\\x=-5,23\end{matrix}\right.\)

\(c,2\left|x\right|-\dfrac{1}{4}=\dfrac{2}{3}\\ \Rightarrow2\left|x\right|=\dfrac{2}{3}+\dfrac{1}{4}\\ \Rightarrow2\left|x\right|=\dfrac{11}{12}\\ \Rightarrow\left|x\right|=\dfrac{11}{12}:2\\ \Rightarrow\left|x\right|=\dfrac{11}{24}\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{11}{24}\\x=-\dfrac{11}{24}\end{matrix}\right.\)

\(d,6-3\left|x\right|=\dfrac{3}{4}\\ \Rightarrow3\left|x\right|=6-\dfrac{3}{4}\\ \Rightarrow3\left|x\right|=\dfrac{21}{4}\\ \Rightarrow\left|x\right|=\dfrac{21}{4}:3\\ \Rightarrow\left|x\right|=\dfrac{7}{4}\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{7}{4}\\x=-\dfrac{7}{4}\end{matrix}\right.\)

\(\left(\dfrac{\sqrt{x}}{\sqrt{x}+2}+\dfrac{8\sqrt{x}+8}{x+2\sqrt{x}}-\dfrac{\sqrt{x}+2}{\sqrt{x}}\right):\left(\dfrac{x+\sqrt{x}+3}{x+2\sqrt{x}}+\dfrac{1}{\sqrt{x}}\right)\left(x>0;x\ne2\right)\\ =\left(\dfrac{\sqrt{x}}{\sqrt{x}+2}+\dfrac{8\sqrt{x}+8}{\sqrt{x}\left(\sqrt{x}+2\right)}-\dfrac{\sqrt{x}+2}{\sqrt{x}}\right):\left(\dfrac{x+\sqrt{x}+3}{\sqrt{x}\left(\sqrt{x}+2\right)}+\dfrac{1}{\sqrt{x}}\right)\\ =\left(\dfrac{\sqrt{x}\cdot\sqrt{x}}{\sqrt{x}\left(\sqrt{x}+2\right)}+\dfrac{8\sqrt{x}+8}{\sqrt{x}\left(\sqrt{x}+2\right)}-\dfrac{\left(\sqrt{x}+2\right)^2}{\sqrt{x}\left(\sqrt{x}+2\right)}\right):\left(\dfrac{x+\sqrt{x}+3}{\sqrt{x}\left(\sqrt{x}+2\right)}+\dfrac{\sqrt{x}+2}{\sqrt{x}\left(\sqrt{x}+2\right)}\right)\)

\(=\dfrac{x+8\sqrt{x}+8-x-\sqrt{x}-4}{\sqrt{x}\left(\sqrt{x}+2\right)}:\dfrac{x+\sqrt{x}+3+\sqrt{x}+2}{\sqrt{x}\left(\sqrt{x}+2\right)}\\ =\dfrac{7\sqrt{x}+4}{\sqrt{x}\left(\sqrt{x+2}\right)}\cdot\dfrac{\sqrt{x}\left(\sqrt{x}+2\right)}{x+2\sqrt{x}+5}\\ =\dfrac{7\sqrt{x}+4}{x+2\sqrt{x}+5}\)

Bài `3`

Cậu tách cho các câu sau nx nhé^^

\(a,x+\dfrac{1}{2}=\dfrac{7}{3}\\ \Rightarrow x=\dfrac{7}{3}-\dfrac{1}{2}\\ \Rightarrow x=\dfrac{14}{6}-\dfrac{3}{6}\\ \Rightarrow x=\dfrac{11}{6}\\ b,\dfrac{2}{5}x-\dfrac{1}{5}=-0,6\\ \Rightarrow\dfrac{2}{5}x=-\dfrac{3}{5}+\dfrac{1}{5}\\ \Rightarrow\dfrac{2}{5}x=-\dfrac{2}{5}\\ \Rightarrow x=-\dfrac{2}{5}:\dfrac{2}{5}\\ \Rightarrow x=-1\\ c,\left(0,5x-\dfrac{3}{7}\right):\dfrac{1}{2}=1\dfrac{1}{7}\\ \Rightarrow\dfrac{1}{2}x-\dfrac{3}{7}=\dfrac{8}{7}\cdot\dfrac{1}{2}\\ \Rightarrow\dfrac{1}{2}x-\dfrac{3}{7}=\dfrac{8}{14}\\ \Rightarrow\dfrac{1}{2}x=\dfrac{4}{7}+\dfrac{3}{7}\\ \Rightarrow\dfrac{1}{2}x=1\\ \Rightarrow x=1:\dfrac{1}{2}\\ \Rightarrow x=2\)

\(d,\dfrac{2}{3}x-\dfrac{2}{5}=\dfrac{1}{2}x-\dfrac{1}{3}\\ \Rightarrow\dfrac{2}{3}x-\dfrac{1}{2}x=-\dfrac{1}{3}+\dfrac{2}{5}\\ \Rightarrow\left(\dfrac{2}{3}-\dfrac{1}{2}\right)x=\dfrac{1}{15}\\ \Rightarrow\dfrac{1}{6}x=\dfrac{1}{15}\\ \Rightarrow x=\dfrac{1}{15}:\dfrac{1}{6}\\ \Rightarrow x=\dfrac{2}{5}\)

`e,1/2 x+2 1/2=3 1/2 x-3/4`

`=> 1/2 x+ 5/2= 7/2x - 3/4`

`=> 1/2x - 7/2x = -3/4 -5/2`

`=> -3x=-13/4`

`=>x=13/12`

\(f,2x\left(x-\dfrac{1}{7}\right)=0\\ \Rightarrow\left[{}\begin{matrix}2x=0\\x-\dfrac{1}{7}=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{7}\end{matrix}\right.\\ g,\left(\dfrac{2x}{5}-1\right):\left(-5\right)=\dfrac{1}{4}\\ \Rightarrow2x:5-1=\dfrac{1}{4}\cdot\left(-5\right)\\ \Rightarrow2x:5-1=-\dfrac{5}{4}\\ \Rightarrow2x:5=-\dfrac{5}{4}+1\\ \Rightarrow2x:5=-\dfrac{1}{14}\\ \Rightarrow2x=-\dfrac{1}{14}\cdot5\\ \Rightarrow2x=-\dfrac{5}{14}\\ \Rightarrow x=-\dfrac{5}{14}:2\\ \Rightarrow x=-\dfrac{5}{28}\)

\(\left(x-1\right)^3=\dfrac{1}{8}\\ \Rightarrow\left(x-1\right)^3=\left(\dfrac{1}{2}\right)^3\\ \Rightarrow x-1=\dfrac{1}{2}\\ \Rightarrow x=\dfrac{1}{2}+1\\ \Rightarrow x=\dfrac{1}{2}+\dfrac{2}{2}\\ \Rightarrow x=\dfrac{3}{2}\)

`a.a.a.a.a.a=a^6`

`4.5.20.20.20=20.20.20.20=20^4`

`3.2.12.12.3= 3.2.3.2.2.3.2.2.3= 3^4 .2^5`

`3.5.27.125= 3.5.3.3.3.5.5.5=3^4 .5^4`

\(d,\left(3x-2\right)^3=64\\ \Rightarrow\left(3x-2\right)^3=4^3\\ \Rightarrow3x-2=4\\ \Rightarrow3x=4+2\\ \Rightarrow3x=6\\ \Rightarrow x=\dfrac{6}{3}=2\\ e,\left(2x+5\right)^4=3^4.5^4\\ \Rightarrow2x+5=3.5\\ \Rightarrow2x+5=15\\ \Rightarrow2x=15-5\\ \Rightarrow2x=10\\ \Rightarrow x=\dfrac{10}{2}=5\\ f,\left(3x+2\right)^3=11.121\\ \Rightarrow\left(3x+2\right)^3=11.11.11\\ \Rightarrow\left(3x+2\right)^3=11^3\\ \Rightarrow3x+2=11\\ \Rightarrow3x=11-2\\ \Rightarrow3x=9\\ \Rightarrow x=\dfrac{9}{3}=3\)

`48/10 = 24/5=4,8`

`213/10=213:10=21,3`

`3/1000=3:1000=0,003`

`25/1000 = 25:1000=0,025`

`647/100=647:100=6,47`

`982/100=982:100=9,82`

`385/10000=385:10000=0,0385`

`982/1000=0,982`

`(-3x^7 y^3 z^2) : (1/3 x^6 yz )`

`= (-3 : 1/3) (x^7:x^6)(y^3 : y)(z^2:z)`

`= -9 xy^2z`