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14 tháng 7 2016
làm 1 bài mẫu nha
a) \(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{25}{6}\)
\(\Rightarrow\frac{1}{3}x=\frac{25}{9}\)
\(\Rightarrow x=\frac{25}{9}:\frac{1}{3}\)
\(\Rightarrow x=\frac{25}{3}\)
các bài sau dễ lắm
14 tháng 7 2016
a) \(\left(\frac{1}{3}x\right):\frac{2}{3}=1\frac{2}{3}:\frac{2}{5}\)
\(\Rightarrow\frac{1}{3}x:\frac{2}{3}=\frac{25}{6}\)
\(\Rightarrow\frac{1}{3}x=\frac{5}{3}\)
\(\Rightarrow x=\frac{5}{3}:\frac{1}{3}\)
\(\Rightarrow x=5\)
HT
25 tháng 7 2017
\(=\frac{16}{5}.\frac{15}{16}-\left(\frac{3}{4}+\frac{2}{7}\right):\left(\frac{-29}{28}\right)\)
\(=3-\left(\frac{21}{28}+\frac{8}{28}\right):\left(\frac{-29}{28}\right)\)
\(=3-\left(\frac{29}{28}\right).\left(\frac{-28}{29}\right)\)
\(=3-\left(-1\right)\)
\(=4\)
b) \(=\left(\frac{1}{4}+\frac{25}{2}-\frac{5}{16}\right):\left(12-\frac{7}{12}:\left(\frac{3}{8}-\frac{1}{12}\right)\right)\)
\(=\left(\frac{4}{16}+\frac{200}{16}-\frac{5}{16}\right):\left(12-\frac{7}{12}:\left(\frac{3.3}{2.3.4}-\frac{2}{2.3.4}\right)\right)\)
\(=\left(\frac{199}{16}\right):\left(12-\frac{7}{12}:\left(\frac{9}{24}-\frac{2}{24}\right)\right)\)
\(=\frac{199}{16}:\left(12-\frac{7}{12}.\frac{24}{7}\right)\)
\(=\frac{199}{16}:\left(12-2\right)\)
\(=\frac{199}{16}:10\)
\(=\frac{199}{160}\)
c) \(\left(\frac{-3}{5}+\frac{5}{11}\right):\frac{-3}{7}+\left(\frac{-2}{5}+\frac{6}{5}\right):\frac{-3}{7}\)
\(\left(\frac{-33}{55}+\frac{25}{55}\right):\frac{-3}{7}+\left(\frac{4}{5}\right):\frac{-3}{7}\)
\(\left(\frac{-8}{55}\right).\frac{-7}{3}+\frac{4}{5}.\frac{-7}{3}\)
\(\frac{-7}{3}\left(\frac{-8}{55}+\frac{4}{5}\right)\)
\(\frac{-7}{3}.\frac{36}{55}=\frac{-84}{55}\)
10 tháng 12 2019
a) \(3,6-\left|x-0,4\right|=0\)
\(\Leftrightarrow\left|x-0,4\right|=3,6\)
\(\Leftrightarrow\left[{}\begin{matrix}x-0,4=3,6\\x-0,4=-3,6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-3,2\end{matrix}\right.\)
Vậy \(x\in\left\{4;-3,2\right\}\)
b) Ta có:
\(\frac{x}{2}=y=\frac{z}{3}=\frac{2y}{2}=\frac{x-2y+z}{2-2+3}=\frac{210}{3}=70\)
\(\Rightarrow\left\{{}\begin{matrix}\frac{x}{2}=70\\y=70\\\frac{z}{3}=70\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=140\\y=70\\z=210\end{matrix}\right.\)
Vậy \(x=140\); \(y=70\); \(z=210\)
c)\(\left|x+0,25\right|-4=\frac{1}{4}\)
\(\Leftrightarrow\left|x+\frac{1}{4}\right|=\frac{17}{4}\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\frac{1}{4}=\frac{17}{4}\\x+\frac{1}{4}=\frac{-17}{4}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=\frac{-9}{2}\end{matrix}\right.\)
Vậy \(x\in\left\{4;\frac{-9}{2}\right\}\)
d) \(x:\left(0,25\right)^4=\left(0,5\right)^2\)
\(\Leftrightarrow x=\left(0,25\right)^4.\left(0,5\right)^2\)
\(\Leftrightarrow x=\left(0,5\right)^8.\left(0,5\right)^2\)
\(\Leftrightarrow x=\left(0,5\right)^{10}=\left(\frac{1}{2}\right)^{10}=\frac{1}{2^{10}}=\frac{1}{1024}\)
Vậy \(x=\frac{1}{1024}\)
e) \(3^{x-1}+5.3^{x-1}=162\)
\(\Leftrightarrow6.3^{x-1}=162\)
\(\Leftrightarrow3^{x-1}=27\)
\(\Leftrightarrow3^{x-1}=3^3\)
\(\Leftrightarrow x-1=3\)
\(\Leftrightarrow x=4\)
f) \(\frac{x}{-25}=\frac{2}{5}\)
\(\Leftrightarrow x=\left(-25\right).\frac{2}{5}=-10\)
Vậy \(x=-10\)
g) \(\left|x+\frac{3}{4}\right|-\frac{3}{4}=\sqrt{\frac{1}{9}}\)
\(\Leftrightarrow\left|x+\frac{3}{4}\right|-\frac{3}{4}=\frac{1}{3}\)
\(\Leftrightarrow\left|x+\frac{3}{4}\right|=\frac{13}{12}\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\frac{3}{4}=\frac{13}{12}\\x+\frac{3}{4}=-\frac{13}{12}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{1}{3}\\x=-\frac{11}{6}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{1}{3};-\frac{11}{6}\right\}\)
VM
10 tháng 12 2019
a) \(3,6-\left|x-0,4\right|=0\)
\(\Rightarrow\left|x-0,4\right|=3,6-0\)
\(\Rightarrow\left|x-0,4\right|=3,6.\)
\(\Rightarrow\left[{}\begin{matrix}x-0,4=3,6\\x-0,4=-3,6\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3,6+0,4\\x=\left(-3,6\right)+0,4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-3,2\end{matrix}\right.\)
Vậy \(x\in\left\{4;-3,2\right\}.\)
c) \(\left|x+0,25\right|-4=\frac{1}{4}\)
\(\Rightarrow\left|x+\frac{1}{4}\right|=\frac{1}{4}+4\)
\(\Rightarrow\left|x+\frac{1}{4}\right|=\frac{17}{4}.\)
\(\Rightarrow\left[{}\begin{matrix}x+\frac{1}{4}=\frac{17}{4}\\x+\frac{1}{4}=-\frac{17}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{17}{4}-\frac{1}{4}\\x=\left(-\frac{17}{4}\right)-\frac{1}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-\frac{9}{2}\end{matrix}\right.\)
Vậy \(x\in\left\{4;-\frac{9}{2}\right\}.\)
d) \(x:\left(0,25\right)^4=\left(0,5\right)^2\)
\(\Rightarrow x:\left(0,25\right)^4=0,25\)
\(\Rightarrow x=\left(0,25\right).\left(0,25\right)^4\)
\(\Rightarrow x=\left(0,25\right)^5\)
\(\Rightarrow x=\frac{1}{1024}\)
Vậy \(x=\frac{1}{1024}.\)
Chúc bạn học tốt!
EC
8 tháng 9 2016
Câu 1:
a)\(\frac{3}{4}-0,25-\left[\frac{7}{3}+\left(-\frac{9}{2}\right)\right]-\frac{5}{6}\)
\(=\frac{3}{4}-\frac{1}{4}-\frac{14}{6}+\frac{27}{6}-\frac{5}{6}\)
\(=\frac{1}{2}-\frac{4}{3}\)
\(=-\frac{5}{6}\)
b)\(7+\left(\frac{7}{12}-\frac{1}{2}+3\right)-\left(\frac{1}{12}+5\right)\)
\(=7+\frac{1}{12}+3-\frac{1}{12}-5\)
\(=5\)
EC
8 tháng 9 2016
Câu 2:
\(\frac{3}{4}-\frac{5}{6}\le\frac{x}{12}< 1-\left(\frac{2}{3}-\frac{1}{4}\right)\)
\(-\frac{1}{12}\le\frac{x}{12}< 1-\frac{5}{12}\)
\(-\frac{1}{12}\le\frac{x}{12}< \frac{7}{12}\)
Vậy -1\(\le\)x<7
XO
22 tháng 9 2021
1.a) \(\left(31\frac{6}{13}+5\frac{9}{41}\right)-36\frac{6}{13}=\left(31+\frac{6}{13}+5+\frac{9}{41}\right)-\left(36+\frac{6}{13}\right)\)
\(=\left(36+\frac{6}{13}-\frac{9}{41}\right)-\left(36+\frac{6}{13}\right)=\left(36+\frac{6}{13}\right)-\left(36+\frac{6}{13}\right)-\frac{9}{41}=-\frac{9}{41}\)
b) \(\frac{5}{3}+\left(-\frac{2}{7}\right)-\left(-1,2\right)-\left|1.4-0,2\right|\)
\(=\frac{5}{3}-\frac{2}{7}+1,2-1,2=\frac{29}{21}\)
c) \(0,25+\frac{3}{5}-\left(\frac{1}{8}-\frac{2}{5}+1\frac{1}{4}\right)+\left|\frac{3}{5}\right|\)
\(=\frac{1}{4}+\frac{3}{5}-\frac{1}{8}+\frac{2}{5}-1-\frac{1}{4}+\frac{3}{5}\)
\(=\left(\frac{1}{4}-\frac{1}{4}\right)+\left(\frac{3}{5}+\frac{2}{5}-1\right)+\frac{3}{5}-\frac{1}{8}=\frac{19}{40}\)
2) \(-\frac{3}{5}-x=0,75\)
=> \(-\frac{3}{5}-x=\frac{3}{4}\)
=> \(x=-\frac{3}{5}-\frac{3}{4}=\frac{-27}{20}\)
b) \(x+\frac{1}{3}=\frac{2}{5}-\left(-\frac{1}{3}\right)\)
=> \(x+\frac{1}{3}=\frac{2}{5}+\frac{1}{3}\)
=> \(x=\frac{2}{5}\)
c) |2x - 4| + 1 = 5
=> |2x - 4| = 4
<=> \(\orbr{\begin{cases}2x-4=4\\2x-4=-4\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=4\\x=0\end{cases}}\)
22 tháng 9 2021
Giúp mình với nha cả nhả :<
Cả nhà làm vài ý thui cx được ạ :<
BA
27 tháng 9 2019
\(a,\left(x-1\right)^3=-125\)
\(\Rightarrow\left(x-1\right)^3=-5^3\)
\(\Rightarrow x-1=-5\)
\(\Rightarrow x=-5+1=-4\)
\(\frac{0,25\cdot x}{x}=\frac{5}{6}:0,125\)
\(\Leftrightarrow\frac{\frac{25}{100}\cdot x}{x}=\frac{5}{6}:\frac{125}{1000}\)
\(\Leftrightarrow\frac{\frac{1}{4}\cdot x}{x}=\frac{5}{6}:\frac{1}{8}\)
\(\Leftrightarrow\frac{\frac{1}{4}\cdot x}{x}=\frac{40}{6}\)
\(\Leftrightarrow\frac{1}{4}\cdot x=\frac{40}{6}\cdot x\)
=> x không thỏa mãn