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VM
23 tháng 7 2019
Bài 1:
1. \(\left(\frac{1^5}{2}\right):\left(\frac{1^8}{2}\right)\)\(=\frac{1^5:1^8}{2:2}=\frac{1}{1}=1.\)
Mình chỉ làm bài 1 thôi nhé.
Chúc bạn học tốt!
N
30 tháng 7 2017
\(\frac{21}{x}=\frac{7}{-4}\Leftrightarrow7x=21.\left(-4\right)\Leftrightarrow7x=-84\Leftrightarrow x=-84:7\Leftrightarrow x=-12\)
\(\frac{114}{2x}=-\frac{8}{12}\Leftrightarrow\frac{57}{x}=-\frac{2}{3}\Leftrightarrow-2x=57.3\Leftrightarrow2x=171\Leftrightarrow x=\frac{171}{2}\)
NB
25 tháng 2 2020
e) \(5^{x+2}=625\\ \Leftrightarrow5^{x+2}=5^4\\ \Leftrightarrow x+2=4\\ \Leftrightarrow x=2\)
Vậy...
g) \(\left(2x-1\right)^3=-8\\ \Leftrightarrow\left(2x-1\right)^3=\left(-2\right)^3\\ \Leftrightarrow2x-1=-2\\ \Leftrightarrow x=-\frac{1}{2}\)
VẬy...
5 tháng 8 2022
2: =>2x-1/4=5/6-1/2x
=>5/2x=5/6+1/4=13/12
=>x=13/30
3: =>3x-5/6=2/3-1/2x
=>3,5x=2/3+5/6=4/6+5/6=9/6=3,2
hay x=32/35
VM
17 tháng 3 2020
Bài 2:
a) \(\frac{8^{14}}{4^{12}}\)
\(=\frac{\left(2^3\right)^{14}}{\left(2^2\right)^{12}}\)
\(=\frac{2^{42}}{2^{24}}\)
\(=2^{18}\)
\(=262144.\)
b) \(\left(-\frac{1}{3}\right)^7.3^7\)
\(=\left[\left(-\frac{1}{3}\right).3\right]^7\)
\(=\left(-1\right)^7\)
\(=-1.\)
c) \(\frac{90^2}{15^2}\)
\(=\left(\frac{90}{15}\right)^2\)
\(=6^2\)
\(=36.\)
d) \(\frac{790^4}{79^4}\)
\(=\left(\frac{790}{79}\right)^4\)
\(=10^4\)
\(=10000.\)
Chúc bạn học tốt!
4 tháng 4 2020
Mk làm tiếp cho bạn Vũ Minh Tuấn nhé!
Bài 1:
\(-\frac{64}{343}=x^3\)
\(\Rightarrow x^3=\left(-\frac{4}{7}\right)^3\)
\(\Rightarrow x=-\frac{4}{7}\)
Vậy \(x=-\frac{4}{7}\)
\(\left(x+20\right)^{100}+\left|y+4\right|=0\)
Ta có: \(\left(x+20\right)^{100}\ge0;\left|y+4\right|\ge0\)
\(\Rightarrow\left\{{}\begin{matrix}\left(x+20\right)^{100}=0\\\left|y+4\right|=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=-20\\y=-4\end{matrix}\right.\)
Vậy \(x=-20;y=-4\)
\(\left(x-\frac{1}{2}\right)^3=\frac{1}{27}\)
\(\Rightarrow\left(x-\frac{1}{2}\right)^3=\left(\frac{1}{3}\right)^3\)
\(\Rightarrow x-\frac{1}{2}=\frac{1}{3}\)
\(\Rightarrow x=\frac{5}{6}\)
Vậy \(x=\frac{5}{6}\)
\(\left(x+\frac{1}{2}\right)^2=\frac{4}{25}\)
\(\Rightarrow\left(x+\frac{1}{2}\right)^2=\left(\frac{2}{5}\right)^2\)
\(\Rightarrow\left[{}\begin{matrix}x+\frac{1}{2}=\frac{2}{5}\\x+\frac{1}{2}=-\frac{2}{5}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-\frac{1}{10}\\x=-\frac{9}{10}\end{matrix}\right.\)
Vậy \(x\in\left\{-\frac{1}{10};-\frac{9}{10}\right\}\)
4 tháng 8 2019
a) \(\frac{1}{4}+\frac{3}{4}x=\frac{3}{4}\Leftrightarrow\frac{3}{4}x=\frac{1}{2}\Leftrightarrow x=\frac{1}{2}\times\frac{4}{3}\Leftrightarrow x=\frac{2}{3}\)
b)\(1\frac{3}{4}x+1\frac{1}{2}=-\frac{4}{5}\Leftrightarrow\frac{7}{4}x+\frac{3}{2}=-\frac{4}{5}\Leftrightarrow\frac{7}{4}x=-\frac{23}{10}\)
\(\Leftrightarrow x=-\frac{23}{10}\times\frac{4}{7}\Leftrightarrow x=-\frac{46}{35}\)
c)\(\frac{3}{4}x+\frac{2}{5}x=1,2\Leftrightarrow x\left(\frac{3}{4}+\frac{2}{5}\right)=1,2\Leftrightarrow\frac{23}{20}x=1,2\)
\(\Leftrightarrow x=1,2\times\frac{20}{23}\Leftrightarrow x=\frac{24}{23}\)
d)\(\frac{3}{7}+\frac{1}{7}:x=\frac{3}{14}\Leftrightarrow\frac{1}{7x}=\frac{3}{14}-\frac{3}{7}\Leftrightarrow\frac{1}{7x}=-\frac{3}{14}\Leftrightarrow14=-3\times7x\)
\(\Leftrightarrow-21x=14\Leftrightarrow x=-\frac{2}{3}\)
e) \(-\frac{3}{4}-\left|\frac{4}{5}-x\right|=-1\Leftrightarrow\left|\frac{4}{5}-x\right|=-\frac{3}{4}+1\Leftrightarrow\left|\frac{4}{5}-x\right|=\frac{1}{4}\)
\(\Leftrightarrow\left[{}\begin{matrix}\frac{4}{5}-x=\frac{1}{4}\\\frac{4}{5}-x=-\frac{1}{4}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{11}{20}\\x=\frac{21}{20}\end{matrix}\right.\)
4 tháng 8 2019
a, \(\frac{1}{4}+\frac{3}{4}x=\frac{3}{4}\\ \Rightarrow\frac{3}{4}x=\frac{1}{2}\\ \Rightarrow x=\frac{2}{3}\)
Vậy \(x=\frac{2}{3}\)
b, \(1\frac{3}{4}x+1\frac{1}{2}=\frac{-4}{5}\\ \frac{7}{4}x+\frac{3}{2}=\frac{-4}{5}\\ \Rightarrow\frac{7}{4}x=\frac{-23}{10}\\ \Rightarrow x=\frac{-46}{35}\)
Vậy \(x=\frac{-46}{35}\)
c, \(\frac{3}{4}x+\frac{2}{5}x=1,2\\ x\left(\frac{3}{4}+\frac{2}{5}\right)=\frac{6}{5}\\ x\cdot\frac{23}{20}=\frac{6}{5}\\ \Rightarrow x=\frac{24}{23}\)
Vậy \(x=\frac{24}{23}\)
d, \(\frac{3}{7}+\frac{1}{7}:x=\frac{3}{14}\\ \Rightarrow\frac{1}{7}:x=\frac{-3}{14}\\ \Rightarrow x=\frac{-2}{3}\)
Vậy \(x=\frac{-2}{3}\)
e, \(\frac{-3}{4}-\left|\frac{4}{5}-x\right|=-1\\ \Rightarrow\left|\frac{4}{5}-x\right|=\frac{1}{4}\\ \Rightarrow\left[{}\begin{matrix}\frac{4}{5}-x=\frac{1}{4}\\\frac{4}{5}-x=\frac{-1}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{11}{20}\\x=\frac{21}{20}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{11}{20};\frac{21}{20}\right\}\)
mình ko bt làm
\(\left(\frac{3}{4}-x\right)^3=\frac{1}{64}\)
\(\Leftrightarrow\left(\frac{3}{4}-x\right)^3=\frac{1}{4}^3\)
\(\Leftrightarrow\frac{3}{4}-x=\frac{1}{4}\)
\(\Leftrightarrow x=\frac{1}{2}\)