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a) Ta có: \(\left(x-1\right)^{x+2}-\left(x-1\right)^{x+4}=0\)

\(\Leftrightarrow\left(x-1\right)^x\cdot\left(x-1\right)^2-\left(x-1\right)^x\cdot\left(x-1\right)^4=0\)

\(\Leftrightarrow\left(x-1\right)^{x+2}\cdot\left[1-\left(x-1\right)^2\right]=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x-1=1\\x-1=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\\x=0\end{matrix}\right.\)

b) Ta có: \(\dfrac{1}{4}\cdot\dfrac{2}{6}\cdot\dfrac{3}{8}\cdot\dfrac{4}{10}\cdot\dfrac{5}{15}\cdot...\cdot\dfrac{30}{62}\cdot\dfrac{31}{64}=2x\)

\(\Leftrightarrow2x=\dfrac{1}{64}\)

hay \(x=\dfrac{1}{128}\)

21 tháng 4 2017

a, \(\dfrac{62}{7}.x=\dfrac{29}{90}.\dfrac{3}{56}\)

\(\dfrac{62}{7}.x=\dfrac{29}{1680}\)

\(x=\dfrac{29}{1680}:\dfrac{62}{7}\)

\(x=\dfrac{29}{14880}\)

b, \(\dfrac{1}{5}:x=\dfrac{1}{5}-\dfrac{1}{7}\)

\(\dfrac{1}{5}:x=\dfrac{2}{35}\)

\(x=\dfrac{1}{5}:\dfrac{2}{35}\)

\(x=\dfrac{7}{2}\)

c, \(\left(x+\dfrac{1}{4}-\dfrac{1}{3}\right):\left(2+\dfrac{1}{6}-\dfrac{1}{4}\right)=\dfrac{7}{46}\)

\(\left(x+\dfrac{1}{4}-\dfrac{1}{3}\right):\left(\dfrac{13}{6}-\dfrac{1}{4}\right)=\dfrac{7}{46}\)

\(\left(x+\dfrac{1}{4}-\dfrac{1}{3}\right):\dfrac{23}{12}=\dfrac{7}{46}\)

\(\left(x+\dfrac{-1}{12}\right):\dfrac{23}{12}=\dfrac{7}{46}\)

\(\left(x+\dfrac{-1}{12}\right)=\dfrac{7}{46}.\dfrac{23}{12}\)

\(x+\dfrac{-1}{12}=\dfrac{7}{24}\)

\(x=\dfrac{7}{24}-\dfrac{-1}{12}\)

\(x=\dfrac{3}{8}\)

3 tháng 1 2019

\(\left(x-3\right)^6-\frac{1}{\frac{1}{3}}=\frac{62}{\frac{1}{3}}\)

\(\left(x-3\right)^6=\frac{62}{\frac{1}{3}}+\frac{1}{\frac{1}{3}}\)

\(\left(x-3\right)^6=62:\frac{1}{3}+1:\frac{1}{3}\)

\(\left(x-3\right)^6=\left(62+1\right):\frac{1}{3}\)

\(\left(x-3\right)^6=63.\frac{1}{3}\)

\(\left(x-3\right)^6=\frac{63}{3}\)

\(\left(x-3\right)^6=21\)

\(\Rightarrow x-3\in\varnothing\)

\(\Rightarrow x\in\varnothing\)

Vậy \(x\in\varnothing\)

17 tháng 7 2016

\(\frac{1}{4}.\frac{2}{6}............\frac{31}{64}=2^x\)

\(\Rightarrow\frac{1.2........31}{2.2.2.3...........2.31.64}=2^x\)

\(\Rightarrow\frac{1}{2^{30}.2^4}=2^x\)

\(\Rightarrow\frac{1}{2^{34}}=2^x\)

\(\Rightarrow x=-34\)

Ta có: \(2^x=\dfrac{1}{4}\cdot\dfrac{2}{6}\cdot\dfrac{3}{8}\cdot\dfrac{4}{10}\cdot\dfrac{5}{12}\cdot...\cdot\dfrac{30}{62}\cdot\dfrac{31}{64}\)

\(\Leftrightarrow2^x=\dfrac{1\cdot2\cdot3\cdot4\cdot...\cdot31}{2\cdot\left(2\cdot3\cdot4\cdot...\cdot31\right)\cdot64}\)

\(\Leftrightarrow2^x=\dfrac{1}{2}\cdot\dfrac{1}{64}=\dfrac{1}{128}\)
\(\Leftrightarrow2^x=\dfrac{1}{2^6}\)

\(\Leftrightarrow2^{x+6}=1\)

\(\Leftrightarrow x+6=0\)

hay x=-6

Vậy: x=-6

3 tháng 4 2021

`1/4 . 2/6 . 3/8 ... . 30/62 .31/64 =2^x`

`-> (1.2.3....30.31)/(4.6.8....62.64)=2^x`

`-> (1.(2.3...31))/(2.(2.3.4...31).32)=2^x`

`-> 1/(2.32)=2^x`

`-> 1/64=2^x`

`-> 1/(2^6)=2^x`

`-> x=-6`.

18 tháng 5 2020

 Heo ơi

Heo