Tìm x:
a)\(\frac{3}{4}+\frac{1}{4}:x=\frac{2}{5}\)
b)|x-2,5|=1,5
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J
1
AT
28 tháng 3 2020
a, x( x - 3) - ( x + 2)( x - 1) = 3
<=> x2 - 3x - x2 + x - 2x + 2 = 3
<=> x2 - 3x - x2 + x - 2x = 3 - 2
<=> -4x = 1
<=> x =\(-\frac{1}{4}\)
Vậy_
b, \(x-\frac{x-1}{5}+\frac{x+2}{6}=4+\frac{x+1}{3}\)
\(\Leftrightarrow\frac{30x}{30}-\frac{\left(x-1\right)6}{30}+\frac{\left(x+2\right)5}{30}=\frac{120}{30}+\frac{\left(x+1\right)10}{30}\)
=> 30x - 6x + 6 + 5x + 10 = 120 + 10x + 10
<=> 30x - 6x + 5x - 10x = 120 + 10 - 6 - 10
<=> 19x = 114
<=> x = 6
Vậy _
26 tháng 9 2019
a ) \(\left|x-2\right|=2\)
\(\Rightarrow\orbr{\begin{cases}x-2=2\\x-2=-2\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=2+2\\x=-2+2\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=4\\x=0\end{cases}}\)
Vậy \(x=4\) hoặc \(x=0\)
b ) \(\left|x-\frac{4}{5}\right|=\frac{3}{4}\)
\(\Rightarrow\orbr{\begin{cases}x-\frac{4}{5}=\frac{3}{4}\\x-\frac{4}{5}=-\frac{3}{4}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{3}{4}+\frac{4}{5}\\x=-\frac{3}{4}+\frac{4}{5}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{15}{20}+\frac{16}{20}\\-\frac{15}{20}+\frac{16}{20}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{31}{20}\\x=\frac{1}{20}\end{cases}}\)
Vậy \(x=\frac{31}{20}\) hoặc \(x=\frac{1}{20}\)
c ) \(6-\left|\frac{1}{2}-x\right|=\frac{2}{5}\)
\(\left|\frac{1}{2}-x\right|=6-\frac{2}{5}\)
\(\left|\frac{1}{2}-x\right|=\frac{28}{5}\)
\(\Rightarrow\orbr{\begin{cases}\frac{1}{2}-x=\frac{28}{5}\\\frac{1}{2}-x=-\frac{28}{5}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{1}{2}-\frac{28}{5}\\x=\frac{1}{2}-\left(-\frac{28}{5}\right)\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-\frac{51}{10}\\x=\frac{61}{10}\end{cases}}\)
Vậy \(x=-\frac{51}{10}\) hoặc \(x=\frac{61}{10}\)
d ) \(\frac{1}{5}-\left|\frac{1}{5}.x\right|=\frac{1}{5}\)
\(\left|\frac{1}{5}.x\right|=\frac{1}{5}-\frac{1}{5}\)
\(\left|\frac{1}{5}.x\right|=0\)
\(\Rightarrow\frac{1}{5}.x=0\)
\(x=0:\frac{1}{5}\)
\(x=0\)
Vậy \(x=0\)
e ) \(-2,5+\left|3x+5\right|=-1,5\)
\(\left|3x+5\right|=-1,5-\left(-2,5\right)\)
\(\left|3x+5\right|=1\)
\(\Rightarrow\orbr{\begin{cases}3x+5=1\\3x+5=-1\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}3x=1-5\\3x=-1-5\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}3x=-4\\3x=-6\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-4:3\\x=-6:3\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-\frac{4}{3}\\x=-2\end{cases}}\)
Vậy \(x=-\frac{4}{3}\) hoặc \(x=-2\)
g ) \(\left(\frac{2}{3}x-1\right)+\left(\frac{3}{4}x+\frac{1}{2}\right)=0\)
\(\Rightarrow\orbr{\begin{cases}\left(\frac{2}{3}x-1\right)=0\\\left(\frac{3}{4}x+\frac{1}{2}\right)=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}\frac{2}{3}x-1=0\\\frac{3}{4}x+\frac{1}{2}=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}\frac{2}{3}x=0+1\\\frac{3}{4}x=0-\frac{1}{2}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}\frac{2}{3}x=1\\\frac{3}{4}x=-\frac{1}{2}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1:\frac{2}{3}\\x=-\frac{1}{2}:\frac{3}{4}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{3}{2}\\x=-\frac{2}{3}\end{cases}}\)
Vậy \(x=\frac{3}{2};x=-\frac{2}{3}\)
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QA
28 tháng 2 2021
Trả lời:
a, | x - 2 | = 2
=> x - 2 = 2 hoặc x - 2 = -2
=> x = 4 x = 0
Vậy x = 4; x = 0
b, \(\left|x-\frac{4}{5}\right|=\frac{3}{4}\)
\(\Rightarrow x-\frac{4}{5}=\frac{3}{4}\)hoặc \(x-\frac{4}{5}=\frac{-3}{4}\)
\(\Rightarrow x=\frac{31}{20}\)hoặc \(x=\frac{1}{20}\)
Vậy \(x=\frac{31}{20};x=\frac{1}{20}\)
c, \(6-\left|\frac{1}{2}-x\right|=\frac{2}{5}\)
\(\Rightarrow\left|\frac{1}{2}-x\right|=\frac{28}{5}\)
\(\Rightarrow\frac{1}{2}-x=\frac{28}{5}\)hoặc \(\frac{1}{2}-x=\frac{-28}{5}\)
\(\Rightarrow x=\frac{-51}{10}\)hoặc \(x=\frac{61}{10}\)
Vậy \(x=\frac{-51}{10};x=\frac{61}{10}\)
d, \(\frac{1}{5}-\left|\frac{1}{5}\cdot x\right|=\frac{1}{5}\)
\(\Rightarrow\left|\frac{1}{5}\cdot x\right|=0\)
\(\Rightarrow\frac{1}{5}\cdot x=0\)
\(\Rightarrow x=0\)
Vậy x = 0
e, \(-2,5+\left|3x+5\right|=-1,5\)
\(\Rightarrow\left|3x+5\right|=1\)
\(\Rightarrow3x+5=1\)hoặc \(3x+5=-1\)
\(\Rightarrow3x=-4\)hoặc \(3x=-6\)
\(\Rightarrow x=\frac{-4}{3}\)hoặc \(x=-2\)
Vậy \(x=\frac{-4}{3};x=-2\)
g, \(\left(\frac{2}{3}x-1\right)+\left(\frac{3}{4}x+\frac{1}{2}\right)=0\)
\(\Rightarrow\frac{2}{3}x-1+\frac{3}{4}x+\frac{1}{2}=0\)
\(\Rightarrow\frac{17}{12}x-\frac{1}{2}=0\)
\(\Rightarrow\frac{17}{12}x=\frac{1}{2}\)
\(\Rightarrow x=\frac{6}{17}\)
Vậy \(x=\frac{6}{17}\)
21 tháng 1 2017
a) \(\frac{3}{4}+\frac{1}{4}.x=\frac{1}{2}+\frac{1}{2}x\)
\(\Rightarrow3.\frac{1}{4}+\frac{1}{4}.x=\frac{1}{2}.\left(x+1\right)\)
\(\Rightarrow\frac{1}{4}.\left(x+3\right)=\frac{1}{2}.\left(x+1\right)\)
\(\Rightarrow\frac{x+1}{x+3}=\frac{1}{4}:\frac{1}{2}=\frac{1}{2}\)\(\Rightarrow\left(x+1\right).2=x+3\Rightarrow2x+2=x+3\)
\(\Rightarrow2x-x=3-2\Rightarrow x=1\)
vay x=1
25 tháng 7 2015
(15/4.4-12/5.5/4)-(7/2:5/2-1/5)-1/5.x=51/5
(15-3)-(7/5-1/5)-1/5.x=51/5
12-6/5-1/5.x=51/5
54/5-1/5.x=51/5
1/5x=54/5-51/5
1/5x=3/5
x=3
27 tháng 4 2019
Bài 2 :
1) \(x-70=-45\) 2) \(\frac{4}{7}:x=\frac{12}{28}\)
\(\Rightarrow\) \(x=-45+70\) \(\Rightarrow x=\frac{4}{7}:\frac{12}{28}\)
\(\Rightarrow\) \(x=25\) \(\Rightarrow x=\frac{4}{3}\)
Vậy \(x=25\) Vậy \(x=\frac{4}{3}\)
3) Giống câu c) ở bài 1
4) \(x-50=-35\) 5) \(\frac{4}{7}.x=\frac{11}{18}\)
\(\Rightarrow x=-35+50\) \(\Rightarrow x=\frac{11}{28}:\frac{4}{7}\)
\(\Rightarrow x=15\) \(\Rightarrow x=\frac{77}{72}\)
Vậy \(x=15\) Vậy \(x=\frac{77}{72}\)
6) \(\left(\frac{2}{3}x+2,5\right):2\frac{2}{6}=6\)
\(\Rightarrow\)\(\left(\frac{2}{3}x+2,5\right):\frac{14}{6}=6\)
\(\Rightarrow\) \(\frac{2}{3}x+2,5=6.\frac{14}{6}\)
\(\Rightarrow\frac{2}{3}x+2,5=14\)
\(\Rightarrow\frac{2}{3}x=\frac{23}{2}\)
\(\Rightarrow x=\frac{23}{2}:\frac{2}{3}\)
\(\Rightarrow x=\frac{69}{4}\)
Vậy \(x=\frac{69}{4}\)
27 tháng 4 2019
Bài 1:
1) \(\frac{7}{5}+\frac{-8}{5}=-\frac{1}{5}\)
2) \(-\frac{6}{5}.\frac{15}{24}=-\frac{3}{4}\)
3) \(\left(\frac{2}{3}+1,5\right)-3,5:7\frac{1}{2}=\)\(\frac{13}{6}-\frac{7}{15}=\frac{17}{10}\)
4) \(\frac{5}{8}-\frac{-7}{9}=\frac{5}{8}+\frac{7}{9}=\frac{101}{72}\)
5)\(\frac{-7}{3}.\frac{12}{28}=-1\)
26 tháng 10 2016
a ) \(\left(\frac{2}{5}-x\right):1\frac{1}{3}+\frac{1}{2}=-4\)
\(\left(\frac{2}{5}-x\right):\frac{4}{3}+\frac{1}{2}=-4\)
\(\left(\frac{2}{5}-x\right):\frac{4}{3}=-4-\frac{1}{2}\)
\(\left(\frac{2}{5}-x\right):\frac{4}{3}=-\frac{9}{2}\)
\(\frac{2}{5}-x=-\frac{9}{2}.\frac{4}{3}\)
\(\frac{2}{5}-x=-3\)
\(x=\frac{2}{5}-\left(-3\right)\)
\(x=\frac{2}{5}+3\)
\(x=\frac{3}{5}-\frac{15}{5}\)
\(x=-\frac{12}{5}\)
Vay \(x=-\frac{12}{5}\)
26 tháng 10 2016
b ) \(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(1+\frac{2}{5}+\frac{2}{3}\right)=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(\frac{15}{15}+\frac{6}{15}+\frac{10}{15}\right)=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(\frac{15+6+10}{15}\right)=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\frac{31}{15}=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right)=-\frac{5}{4}.\frac{31}{15}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right)=-\frac{1}{4}.\frac{31}{3}\)
\(-3+\frac{3}{x}-\frac{1}{3}=-\frac{31}{12}\)
\(-3+\frac{3}{x}=-\frac{31}{12}+\frac{1}{2}\)
\(-3+\frac{3}{x}=-\frac{31}{12}+\frac{6}{12}\)
\(-3+\frac{3}{x}=\frac{-25}{12}\)
\(\frac{3}{x}=\frac{-25}{12}+3\)
\(\frac{3}{x}=\frac{-25}{12}+\frac{36}{12}\)
\(\frac{3}{x}=\frac{5}{6}\)
\(\frac{18}{6x}=\frac{5x}{6x}\)
Đèn dây , bạn tự làm tiếp nhé , de rồi chứ
29 tháng 8 2017
Ta có : \(\left(5x-3\right)\left(2x+5\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}5x-3=0\\2x+5=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}5x=3\\2x=-5\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=\frac{3}{5}\\x=-\frac{5}{2}\end{cases}}\)
\(a,\frac{3}{4}+\frac{1}{4}:x=\frac{2}{5}\)
\(\Leftrightarrow\frac{1}{4}:x=\frac{2}{5}-\frac{3}{4}\)
\(\Leftrightarrow\frac{1}{4}:x=\frac{8}{20}-\frac{15}{20}\)
\(\Leftrightarrow\frac{1}{4}:x=\frac{-7}{20}\)
\(\Leftrightarrow x=\frac{1}{4}.\frac{20}{-7}\)
\(\Leftrightarrow x=\frac{20}{-28}\)
\(b,|x-2,5|=1,5\)
\(\Leftrightarrow\orbr{\begin{cases}x-2,5=1,5\\x-2,5=-1,5\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=1,5+2,5\\x=-1,5+2,5\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=3\\x=1\end{cases}}\)