Tìm x, biết :
a) \(\left[x-2\right]=x\)
b) \(\left[x-3,4\right]+\left[2,6-x\right]=0\)
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NT
4
24 tháng 3 2017
a ) ĐK : \(x\ge0\)
Ta có : \(\left|x-2\right|=x-2\) hoặc \(\left|x-2\right|=2-x\)
TH1 : \(x-2=0\Rightarrow x=2\left(TM\right)\)
TH2 : \(2-x=0\Rightarrow x=2\left(TM\right)\)
Vậy \(x=2\)
b ) Vì \(\left|x-3,4\right|\ge0;\left|2,6-x\right|\ge0\)
\(\Rightarrow\left|x-3,4\right|+\left|2,6-x\right|\ge0\)
Để \(\left|x-3,4\right|+\left|2,6-x\right|=0\) khi \(\left|x-3,4\right|=0;\left|2,6-x\right|=0\)
\(\Rightarrow x=3,4;x=2,6\) \(\Rightarrow x=\varphi\)
24 tháng 3 2017
a. Câu a có thể x=1 nữa.
b, \(\hept{\begin{cases}x=3,6\\x=2,6\end{cases}}\)
19 tháng 6 2022
c: =>x+5=-4
=>x=-9
d: =>2x-3=3 hoặc 2x-3=-3
=>2x=6 hoặc 2x=0
=>x=3 hoặc x=0
22 tháng 2 2022
a: =>2x-1=-2
=>2x=-1
hay x=-1/2
b: \(\Leftrightarrow\left[{}\begin{matrix}3x+2=0\\-\dfrac{2}{5}x-7=0\end{matrix}\right.\Leftrightarrow x\in\left\{-\dfrac{2}{3};-\dfrac{35}{2}\right\}\)
c: x/8=9/4
nên x/8=18/8
hay x=18
d: \(\Leftrightarrow\left(x-3\right)^2=36\)
=>x-3=6 hoặc x-3=-6
=>x=9 hoặc x=-3
e: =>-1,7x=6,12
hay x=-3,6
h: =>x-3,4=27,6
hay x=31
R
22 tháng 2 2022
a) \(\dfrac{1}{3}\div\left(2x-1\right)=\dfrac{-1}{6}\)
\(\left(2x-1\right).\dfrac{1}{3}\div\left(2x-1\right)=\left(2x-1\right)\left(-\dfrac{1}{6}\right)\)
\(\dfrac{1}{3}=\left(2x-1\right)\left(-\dfrac{1}{6}\right)\)
\(\dfrac{1}{3}=-1\left(2x-1\right)\div6\)
\(\dfrac{1}{3}=-2x+1\div6\)
\(x=-\dfrac{1}{2}\)
b) \(\left(3x+2\right)\left(\dfrac{-2}{5}x-7\right)=0\)
\(TH1:3x+2=0\)
\(3x=0-2\)
\(3x=-2\)
\(x=\dfrac{-2}{3}\)
\(TH2:\left(-\dfrac{2}{5}x-7\right)=0\)
\(\left(\dfrac{-2}{5}x-7\right)=0\)
\(\left(\dfrac{-2x}{5}+\dfrac{5\left(-7\right)}{5}\right)=0\)
\(\left(\dfrac{-2x-35}{5}\right)=0\)
\(-2x-35=0\)
\(-2x=0+35\)
\(x=-\dfrac{35}{2}\)
c) \(\dfrac{x}{8}=\dfrac{9}{4}\)
\(\Leftrightarrow x=\dfrac{9.8}{4}=\dfrac{72}{4}=18\)
\(x=18\)
d) \(\dfrac{x-3}{2}=\dfrac{18}{x-3}\)
\(x-3=18+2\)
\(x=20-3\)
\(x=17\)
e) \(4,5x-6,2x=6,12\)
\(\dfrac{9x}{2}-6,2.x=6,12\)
\(\dfrac{9x}{2}+\dfrac{-31x}{5}=6,12\)
\(\dfrac{5.9x}{10}+\dfrac{2\left(-31\right)x}{10}=6.12\)
\(\dfrac{45x-62x}{10}=6.12\)
\(=-17x\div10=6.12\)
\(-17x=10.6.12\)
\(x=-3,6\)
h) \(11,4-\left(x-3,4\right)=-16,2\)
\(x-3,4=-16,2+11,4\)
\(x-3,4=-4,8\)
\(x=-1,4\)
NX
0
19 tháng 6 2022
Câu 2:
\(2^{24}=8^8< 9^8=3^{16}\)
Câu 2:
c: =>x+5=-4
=>x=-9
d: =>2x-3=3 hoặc 2x-3=-3
=>2x=6 hoặc 2x=0
=>x=0 hoặc x=3
25 tháng 7 2021
a/ \(x=\dfrac{-5}{12}\)
b/ \(x\approx-1,9526\)
c/ \(x=\dfrac{21-i\sqrt{199}}{10}\)
d/ \(x=\dfrac{-20}{13}\)
26 tháng 12 2021
a) \(\Rightarrow\dfrac{1}{3}x\left(x-2\right)\left(x+2\right)=0\Rightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)
b) \(\Rightarrow\left(x+5\right)\left(x-1\right)=0\Rightarrow\left[{}\begin{matrix}x=-5\\x=1\end{matrix}\right.\)
c) \(\Rightarrow x\left(x^2-\dfrac{1}{9}\right)=0\Rightarrow x\left(x-\dfrac{1}{3}\right)\left(x+\dfrac{1}{3}\right)=0\Rightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{3}\\x=-\dfrac{1}{3}\end{matrix}\right.\)
e) \(\Rightarrow\left(x+2\right)\left(x+2-x+2\right)=0\Rightarrow\left(x+2\right).4=0\Rightarrow x=-2\)
f) \(\Rightarrow x\left(2x-3\right)+2\left(2x-3\right)=0\Rightarrow\left(2x-3\right)\left(x+2\right)=0\Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=-2\end{matrix}\right.\)
g) \(\Rightarrow2\left(3x-2\right)^2-\left(3x-2\right)\left(3x+2\right)=0\Rightarrow\left(3x-2\right)\left(3x-6\right)=0\Rightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=2\end{matrix}\right.\)
h) \(\Rightarrow x\left(x+1\right)\left(x+2\right)=0\Rightarrow\left[{}\begin{matrix}x=0\\x=-1\\x=-2\end{matrix}\right.\)
i) \(\Rightarrow4x\left(x+1\right)+5\left(x+1\right)=0\Rightarrow\left(x+1\right)\left(4x+5\right)=0\Rightarrow\left[{}\begin{matrix}x=-1\\x=-\dfrac{5}{4}\end{matrix}\right.\)
24 tháng 7 2016
b, \(\Leftrightarrow x\left(x-3\right)+\left(x+1\right)\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(x+x+1\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(2x+1\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x-3=0\\2x+1=0\end{array}\right.\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=3\\2x=-1\end{array}\right.\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=3\\x=\frac{-1}{2}\end{array}\right.\)
24 tháng 7 2016
a) |x-y|+|x-9|=0
=>
| |x-y| | 0 |
| |x-9| | 0 |
| x | 9;-9 |
| y | 9;-9 |
b) |x2-3x|+|(x+1).(x-3)|=0
xét x2-3x|=0
=> x2-3x=0
x(x-3)=0
=>x=0 hoặc x-3=0
=> x=3
|(x+1)(x-3)|=0
=> (x+1)(x-3)=0
th1 x=0
(0+1).(0-3)=0
-1.(-3)=0(loại)
th2 x=3
(3+1)(3-3)=0
4.0=0 (lấy)
=> x=0
Nguyễn Huy Tú
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