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29 tháng 7 2021
a) Ta có: \(\dfrac{4}{5}-3\left|x\right|=\dfrac{1}{5}\)
\(\Leftrightarrow3\left|x\right|=\dfrac{4}{5}-\dfrac{1}{5}=\dfrac{3}{5}\)
\(\Leftrightarrow\left|x\right|=\dfrac{1}{5}\)
hay \(x\in\left\{\dfrac{1}{5};-\dfrac{1}{5}\right\}\)
b) Ta có: \(4x-\dfrac{1}{2}x+\dfrac{3}{5}x=\dfrac{4}{5}\)
nên \(\dfrac{41}{10}x=\dfrac{4}{5}\)
hay \(x=\dfrac{8}{41}\)
c) Ta có: \(\left(2x-8\right)\left(10-5x\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-8=0\\10-5x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=8\\5x=10\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=2\end{matrix}\right.\)
d) Ta có: \(\dfrac{3}{4}+\dfrac{1}{4}\left|2x-1\right|=\dfrac{7}{2}\)
\(\Leftrightarrow\dfrac{1}{4}\left|2x-1\right|=\dfrac{7}{2}-\dfrac{3}{4}=\dfrac{14}{4}-\dfrac{3}{4}=\dfrac{11}{4}\)
\(\Leftrightarrow\left|2x-1\right|=11\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-1=11\\2x-1=-11\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=12\\2x=-10\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-5\end{matrix}\right.\)
NA
1
11 tháng 10 2021
a) \(3\dfrac{4}{5}:\dfrac{8}{5}=0,25:x\)
\(\Rightarrow\dfrac{19}{5}.\dfrac{5}{8}=\dfrac{x}{4}\)
\(\Rightarrow\dfrac{x}{4}=2\Rightarrow x=8\)
b) \(2x+\dfrac{3}{24}=3x-\dfrac{1}{32}\)
\(\Rightarrow x=\dfrac{1}{8}+\dfrac{1}{32}=\dfrac{5}{32}\)
c) \(\dfrac{13x-2}{2x+5}=\dfrac{76}{17}\)
\(\Rightarrow221x-34=152x+380\)
\(\Rightarrow69x=414\Rightarrow x=6\)
N
1 tháng 8 2019
\(\left(\frac{3}{4}x-\frac{1}{2}\right).\left(0,25x+\frac{4}{3}\right)=0\)
\(\left(\frac{3}{4}x-\frac{1}{2}\right).\left(\frac{1}{4}x+\frac{4}{3}\right)=0\)
TH1: \(\frac{3}{4}x-\frac{1}{2}=0\)
\(\frac{3}{4}x=\frac{1}{2}\)
\(x=\frac{2}{3}\)
TH2: \(\frac{1}{4}x+\frac{4}{3}=0\)
\(\frac{1}{4}x=-\frac{4}{3}\)
\(x=-\frac{16}{3}\)
Vậy \(x\in\text{{}\frac{2}{3};-\frac{16}{3}\)}
BA
1 tháng 8 2019
\(\left(\frac{3}{4}x-\frac{1}{2}\right)\left(0,25x+\frac{4}{3}\right)=0\)
\(\Rightarrow\left(\frac{3}{4}x-\frac{1}{2}\right)\left(\frac{1}{4}x+\frac{4}{3}\right)=0\)
\(\Rightarrow\orbr{\begin{cases}\frac{3}{4}x-\frac{1}{2}=0\\\frac{1}{4}x+\frac{4}{3}=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}\frac{3}{4}x=\frac{1}{2}\\\frac{1}{4}x=-\frac{4}{3}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{2}{3}\\x=-\frac{16}{3}\end{cases}}\)
Vậy...
17 tháng 7 2021
a) Ta có: \(\dfrac{1}{4}-\left|x+\dfrac{1}{2}\right|=\dfrac{1}{8}\)
\(\Leftrightarrow\left|x+\dfrac{1}{2}\right|=\dfrac{1}{8}\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{2}=\dfrac{1}{8}\\x+\dfrac{1}{2}=-\dfrac{1}{8}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-3}{8}\\x=\dfrac{-5}{8}\end{matrix}\right.\)
15 tháng 1 2022
\(a,\dfrac{-3}{4}x+1=\dfrac{5}{6}\\ \Rightarrow\dfrac{-3}{4}x=\dfrac{-1}{6}\\ \Rightarrow x=\dfrac{2}{9}\\ b,\left(2x-3\right)\left(x-5\right)=0\\ \Rightarrow\left[{}\begin{matrix}2x-3=0\\x-5=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=5\end{matrix}\right.\\ c,\dfrac{1}{2}-\left|x+1\right|=0,25\\ \Rightarrow\left|x+1\right|=0,25\\ \Rightarrow\left[{}\begin{matrix}x+1=0,25\\x+1=-0,25\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-0,75\\x=-1,25\end{matrix}\right.\)
15 tháng 1 2022
a: =>-3/4x=-1/6
hay x=2/9
b: =>2x-3=0 hoặc x-5=0
hay x=3/2 hoặc x=5
c: =>|x+1|=1/4
\(\Leftrightarrow x+1\in\left\{\dfrac{1}{4};-\dfrac{1}{4}\right\}\)
hay \(x\in\left\{-\dfrac{3}{4};-\dfrac{5}{4}\right\}\)
NT
4
3 tháng 9 2018
a, \(7\left(x-1\right)+2x\left(1-x\right)=0\)
\(\Rightarrow\left(7-2x\right)\left(x-1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}7-2x=0\\x-1=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{7}{2}\\x=1\end{cases}}\)
b, \(0,25-\left|3,5-x\right|=0\)
\(\Rightarrow\left|3,5-x\right|=2,5\)
\(\Rightarrow\orbr{\begin{cases}3,5-x=2,5\\3,5-x=-2,5\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1\\x=6\end{cases}}\)
c, \(\left|x+\frac{3}{4}\right|-\frac{1}{2}=0\)
\(\Rightarrow\left|x+\frac{3}{4}\right|=\frac{1}{2}\)
\(\Rightarrow\orbr{\begin{cases}x+\frac{3}{4}=\frac{1}{2}\\x+\frac{3}{4}=\frac{-1}{2}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{-1}{4}\\x=\frac{-5}{4}\end{cases}}\)
3 tháng 9 2018
a) 7.(x-1) + 2x.(1-x) = 0
7.(x-1) - 2x.(x-1) = 0
(x-1).(7-2x) = 0
=> (x-1) = 0 => x = 1
7-2x = 0 => 2x = 7 => x = 7/2
KL:...
b) 0,25 - | 3,5-x| = 0
=> |3,5 - x| = 0,25
TH1: 3,5 - x = 0,25
x = 3,25
TH2: 3,5 - x = -0,25
x = 3,75
phần c bn dựa vào phần b mak lm nha
22 tháng 6 2016
\(a,\left(\frac{3}{8}+-\frac{3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
= \(\left(-\frac{3}{8}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
= \(\frac{5}{24}:\frac{5}{6}+\frac{1}{2}\)
= \(\frac{1}{4}+\frac{1}{2}\)
= \(\frac{3}{4}\)
b)\(-\frac{7}{3}.\frac{5}{9}+\frac{4}{9}.\left(-\frac{3}{7}\right)+\frac{17}{7}\)
=\(-\frac{35}{27}+\left(-\frac{4}{21}\right)+\frac{17}{7}\)
= \(-\frac{35}{27}+\frac{47}{21}\)
= \(\frac{178}{189}\)
c) \(\frac{117}{13}-\left(\frac{2}{5}+\frac{57}{13}\right)\)
= \(\frac{117}{13}-\frac{311}{65}\)
= \(\frac{274}{65}\)
d) \(\frac{2}{3}-0,25:\frac{3}{4}+\frac{5}{8}.4\)
= \(\frac{2}{3}-\frac{1}{4}:\frac{3}{4}+\frac{5}{8}.4\)
= \(\frac{2}{3}-\frac{1}{3}+\frac{5}{2}\)
= \(\frac{1}{3}+\frac{5}{2}\)
= \(\frac{17}{6}\)
PT
29 tháng 5 2021
a) A(x) = 5x4 - 5 + 6x3 + x4 - 5x - 12
= (5x4 + x4) + (- 5 - 12) + 6x3 - 5x
= 6x4 - 17 + 6x3 - 5x
= 6x4 + 6x3 - 5x - 17
B(x) = 8x4 + 2x3 - 2x4 + 4x3 - 5x - 15 - 2x2
= (8x4 - 2x4) + (2x3 + 4x3) - 5x - 15 - 2x2
= 4x4 + 6x3 - 5x - 15 - 2x2
= 4x4 + 6x3 - 2x2 - 5x - 15
b) C(x) = A(x) - B(x)
= 6x4 + 6x3 - 5x - 17 - (4x4 + 6x3 - 2x2 - 5x - 15)
= 6x4 + 6x3 - 5x - 17 - 4x4 - 6x3 + 2x2 + 5x + 15
= ( 6x4 - 4x4) + ( 6x3 - 6x3) + (- 5x + 5x) + (-17 + 15) + 2x2
= 2x4 - 2 + 2x2
= 2x4 + 2x2 - 2
BD
1
TT
22 tháng 12 2017
a,\(\left(0,5x-\dfrac{3}{7}\right):\dfrac{1}{2}=1\dfrac{1}{7}\)
\(0,5x-\dfrac{3}{7}=\dfrac{4}{7}\)
\(0,5x=1\)
\(x=2\)
b,Đề chưa rõ,bạn viết lại nhé!
c,\(\left(\dfrac{1}{5}-\dfrac{3}{2}x\right)^2=\dfrac{9}{4}\)
\(\dfrac{1}{5}-\dfrac{3}{2}x=\dfrac{3}{2}\)
\(\dfrac{3}{2}x=-\dfrac{13}{10}\)
\(x=-\dfrac{13}{15}\)
\(a,\frac{-2}{3}x=8\)<=> \(x=-12\)
\(b,\frac{1}{4}:x=-3+\frac{3}{4}\)<=>\(\frac{1}{4}:x=\frac{-9}{4}\)<=>\(x=-9\)
\(c,\orbr{\begin{cases}2x-\frac{1}{3}=0\\0.5x+0.25=0\end{cases}}\)<=>\(\orbr{\begin{cases}x=\frac{1}{6}\\x=\frac{-3}{4}\end{cases}}\)
a) \(\frac{-2}{3}x+4=12\)
\(\Rightarrow\frac{-2}{3}x=12-4\)
\(\Rightarrow\frac{-2}{3}x=8\)
\(\Rightarrow x=8:\frac{-2}{3}\)
\(\Rightarrow x=-12\)
Vậy x = -12
b) \(\frac{-3}{4}+\frac{1}{4}:x=-3\)
\(\Rightarrow\frac{1}{4}:x=-3-\left(\frac{3}{4}\right)\)
\(\Rightarrow\frac{1}{4}:x=\frac{-9}{4}\)
\(\Rightarrow x=\frac{1}{4}:\frac{-9}{4}\)
\(\Rightarrow x=\frac{-1}{9}\)
Vậy \(x=\frac{-1}{9}\)
c) \(\left(2x-\frac{1}{3}\right)\left(0,5x+0,25\right)=0\)
\(\Rightarrow\orbr{\begin{cases}2x-\frac{1}{3}=0\\0,5x+0,25=0\end{cases}}\Rightarrow\orbr{\begin{cases}2x=\frac{1}{3}\\0,5x=-0,25\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{1}{6}\\x=-0,5\end{cases}}\)
Vậy \(x=\frac{1}{6}\)hoặc \(x=-0,5\)
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