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30 tháng 8 2022
a: =>2/3-1/3x+1/2-x-1/2=5
=>-4/3x+2/3=5
=>-4/3x=13/3
=>x=-13/4
b: \(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{2}=0\\x-\dfrac{3}{4}=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=\dfrac{3}{4}\end{matrix}\right.\)
c: =>1/3x+3/5x+3/5=0
=>14/15x=-3/5
=>x=-3/5:14/15=-3/5x15/14=-45/70=-9/14
d: =>x>8/2
e: =>x:1/45=1/2
=>x=1/90
g: =>1/2:x=-2/15
=>x=-1/2:2/15=-15/4
12 tháng 7 2019
\(a,\frac{1}{3}+\frac{1}{2}:x=\frac{1}{5}\)
\(\Leftrightarrow\frac{1}{2}:x=\frac{1}{5}-\frac{1}{3}\)
\(\Leftrightarrow\frac{1}{2}:x=\frac{3}{15}-\frac{5}{15}\)
\(\Leftrightarrow\frac{1}{2}:x=\frac{-2}{15}\)
\(\Leftrightarrow x=\frac{1}{2}:\frac{-15}{2}=\frac{-15}{4}\)
12 tháng 7 2019
\(b,\frac{1}{3}x+\frac{2}{5}\left[x+1\right]=0\)
\(\Leftrightarrow\frac{1}{3}x+\frac{2}{5}x+\frac{2}{5}=0\)
\(\Leftrightarrow\frac{11}{15}x=-\frac{2}{5}\Leftrightarrow x=\frac{-2}{5}:\frac{11}{15}=\frac{-2}{5}\cdot\frac{15}{11}=\frac{-2}{1}\cdot\frac{3}{11}=\frac{-6}{11}\)
6 tháng 8 2022
a: =>(3/2-2x):2/3=1/6
=>3/2-2x=1/6x2/3=2/18=1/9
=>2x=25/18
hay x=25/36
b: \(\Leftrightarrow2x-2x+\dfrac{5}{2}-2=x-\dfrac{1}{4}\)
=>x-1/4=1/2
=>x=3/4
c: \(\Leftrightarrow2x-\dfrac{2}{3}-\dfrac{1}{3}x+\dfrac{1}{4}x=0\)
=>23/12x=2/3
=>x=8/23
LT
1
5 tháng 8 2019
a) \(\frac{2}{3}-\frac{1}{3}\left(x-\frac{3}{2}\right)-\frac{1}{2}\left(2x+1\right)=5\)
\(\Leftrightarrow-\frac{1}{3}\left(x-\frac{3}{2}\right)-\frac{1}{2}\left(2x+1\right)=5-\frac{2}{3}\)
\(\Leftrightarrow-\frac{1}{3}\left(x-\frac{3}{2}\right)-\frac{1}{2}\left(2x+1\right)=\frac{13}{3}\)
\(\Leftrightarrow-\frac{1}{3}\left(x-\frac{3}{2}\right).6-\frac{1}{2}\left(2x-1\right).6=\frac{13}{3}.6\)
\(\Leftrightarrow-2\left(x-\frac{3}{2}\right)-2\left(2x+1\right)=26\)
\(\Leftrightarrow-8x=26\)
\(\Leftrightarrow x=\frac{26}{-8}=\frac{13}{-4}\)
\(\Rightarrow x=-\frac{13}{4}\)
b) \(\left(x+\frac{1}{2}\right)\left(x-\frac{3}{4}\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{2}=0\\x-\frac{3}{4}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-\frac{1}{2}\\x=\frac{3}{4}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-\frac{1}{2}\\x=\frac{3}{4}\end{cases}}\)
c) \(\frac{1}{3}.x+\frac{2}{5}-\left(x+1\right)=0\)
\(\Leftrightarrow\frac{1}{3}.x+\frac{2}{5}-x-1=0\)
\(\Leftrightarrow\frac{x}{3}+\frac{2}{5}-x-1=0\)
\(\Leftrightarrow-\frac{2x}{3}=\frac{3}{5}\)
\(\Leftrightarrow x=\frac{3}{5}:-\frac{2}{3}\)
\(\Leftrightarrow x=-\frac{9}{10}\)
\(\Rightarrow x=-\frac{9}{10}\)
5 tháng 9 2016
bạn cho nhìu ứa nên mik trả lời vài câu nha:
1.
A. Vì |x- 1/2| >=0 => Amin =0
B.Vì |x + 3/4| >=0 => B >= 2 (cộng 2 mà) => Bmin =2 khi x+ 3/4 =0 ....
các câu còn lại làm tương tự nhé
17 tháng 10 2020
a) \(\frac{2}{3}x-\frac{2}{5}=\frac{1}{2}x-\frac{1}{3}\)
=> \(\frac{2}{3}x-\frac{2}{5}-\frac{1}{2}x+\frac{1}{3}=0\)
=> \(\left(\frac{2}{3}x-\frac{1}{2}x\right)+\left(-\frac{2}{5}+\frac{1}{3}\right)=0\)
=> \(\frac{1}{6}x-\frac{1}{15}=0\Rightarrow\frac{1}{6}x=\frac{1}{15}\Rightarrow x=\frac{1}{15}:\frac{1}{6}=\frac{1}{15}\cdot6=\frac{2}{5}\)
Vậy x = 2/5
b) \(\frac{1}{3}x+\frac{2}{5}\left(x+1\right)=0\)
=> \(\frac{1}{3}x+\frac{2}{5}x+\frac{2}{5}=0\)
=> \(\frac{11}{15}x+\frac{2}{5}=0\Rightarrow\frac{11}{15}x=-\frac{2}{5}\)
=> \(x=\left(-\frac{2}{5}\right):\frac{11}{15}=\left(-\frac{2}{5}\right)\cdot\frac{15}{11}=-\frac{6}{11}\)
Vậy x = -6/11
c) \(\frac{2}{3}-\frac{1}{3}\left(x-\frac{3}{2}\right)-\frac{1}{2}\left(2x+1\right)=5\)
=> \(\frac{2}{3}-\frac{1}{3}x+\frac{1}{2}-x-\frac{1}{2}=5\)
=> \(\left(\frac{2}{3}+\frac{1}{2}-\frac{1}{2}\right)+\left(-\frac{1}{3}x-x\right)=5\)
=> \(\frac{2}{3}-\frac{4}{3}x=5\)
=> \(\frac{4}{3}x=-\frac{13}{3}\Rightarrow x=\left(-\frac{13}{3}\right):\frac{4}{3}=\left(-\frac{13}{3}\right)\cdot\frac{3}{4}=-\frac{13}{4}\)
Vậy x = -13/4
d) \(\frac{11}{5}-\left(\frac{7}{9}-x\right)\cdot\frac{3}{8}=\frac{61}{90}+\frac{x}{3}\)
=> \(\frac{11}{5}-\frac{3}{8}\left(\frac{7}{9}-x\right)=\frac{61}{90}+\frac{30x}{90}\)
=> \(\frac{11}{5}-\frac{7}{24}+\frac{3}{8}x=\frac{61+30x}{90}\)
=> \(\frac{229}{120}+\frac{3}{8}x=\frac{61+30x}{90}\)
=> \(\frac{229}{120}+\frac{3x}{8}=\frac{61+30x}{90}\)
=> \(\frac{229}{120}+\frac{45x}{120}=\frac{61+30x}{90}\)
=> \(\frac{229+45x}{120}=\frac{61+30x}{90}\)
=> \(\frac{3\left(229+45x\right)}{360}=\frac{4\left(61+30x\right)}{360}\)
=> \(3\left(229+45x\right)=4\left(61+30x\right)\)
=> \(687+135x=244+120x\)
=> \(687+135x-244-120x=0\)
=> \(\left(687-244\right)+\left(135x-120x\right)=0\)
=> \(443+15x=0\)
=> \(15x=-443\Rightarrow x=-\frac{443}{15}\)
Vậy x = -443/15
26 tháng 5 2022
Bài 2:
a: \(A=-\left(x-2\right)^2+3\le3\)
Dấu '=' xảy ra khi x=2
b: \(B=-\left(2x-3\right)^2+\dfrac{1}{2}\le\dfrac{1}{2}\)
Dấu '=' xảy ra khi x=3/2
c: \(C=-\left(2x-\dfrac{3}{5}\right)^2-\dfrac{1}{3}\le-\dfrac{1}{3}\)
Dấu '=' xảy ra khi x=3/10
d: \(D=-\left|\dfrac{5}{3}-x\right|\le0\)
Dấu '=' xảy ra khi x=5/3
e: \(E=-\left|x-\dfrac{1}{10}\right|+9\le9\)
Dấu '=' xảy ra khi x=1/10
f: \(F=-\left|\dfrac{1}{2}x+1\right|-\dfrac{2}{3}\le-\dfrac{2}{3}\)
Dấu '=' xảy ra khi x=-2
`#040911`
`b)`
\(x+\dfrac{1}{2}-x-\dfrac{2}{3}=\dfrac{1}{2}\\ \Rightarrow x+\dfrac{1}{2}-x-\dfrac{2}{3}-\dfrac{1}{2}=0\\ \Rightarrow\left(x-x\right)+\left(\dfrac{1}{2}-\dfrac{2}{3}-\dfrac{1}{2}\right)=0\\ \Rightarrow-\dfrac{2}{3}=0\left(\text{vô lý}\right)\\ \text{Vậy, }x\in\varnothing\)
`c)`
\(\left|x+1\right|=5\\ \Rightarrow\left[{}\begin{matrix}x+1=5\\x+1=-5\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=5-1\\x=-5-1\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=4\\x=-6\end{matrix}\right.\\ \text{Vậy, }x\in\left\{-6;4\right\}.\)
\(x+\dfrac{1}{2}-x-\dfrac{2}{3}=\dfrac{1}{2}\\ -\dfrac{2}{3}=\dfrac{1}{2}-\dfrac{1}{2}\\ -\dfrac{2}{3}=0\left(vô.lí\right)\\ Không.x.thoả\\ ----\\ \left|x+1\right|=5\\ \Leftrightarrow\left[{}\begin{matrix}x+1=5\\x+1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-6\end{matrix}\right.\)