TÌM X
X x 10 - x =1
giúp mình nhớ
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\(\left|x-3\right|-2x=1\left(đk:x\ge-\dfrac{1}{2}\right)\)
\(\Leftrightarrow\left|x-3\right|=1+2x\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=1+2x\left(x\ge3\right)\\x-3=-1-2x\left(-\dfrac{1}{2}\le x< 3\right)\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\left(loại\right)\\x=\dfrac{2}{3}\left(tm\right)\end{matrix}\right.\)
\(\Leftrightarrow\left|3x-2\right|>x+1\)
\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}3x-2>0\\x+1< 0\end{matrix}\right.\\\left\{{}\begin{matrix}x+1>0\\3x-2>x^2+2x+1\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>-1\\x^2+2x+1-3x+2< 0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>-1\\x^2-x+3< 0\end{matrix}\right.\Leftrightarrow x\in\varnothing\)
\(\left(\dfrac{1}{15}+\dfrac{1}{35}+\dfrac{1}{63}\right)x=1\)
\(\Leftrightarrow\dfrac{1}{9}x=1\)
\(\Leftrightarrow x=1:\dfrac{1}{9}\)
\(\Leftrightarrow x=9\)
=>1/2(2/15+2/35+2/63)*x=1
=>1/2(1/3-1/5+1/5-1/7+1/7-1/9)*x=1
=>1/2*2/9*x=1
=>x*1/9=1
=>x=9
\(x-\dfrac{1}{2}=\dfrac{4}{7}\\ x=\dfrac{4}{7}+\dfrac{1}{2}\\ x=\dfrac{15}{14}\\ \dfrac{19}{7}-x=\dfrac{27}{2}-1\\ \dfrac{19}{7}-x=\dfrac{25}{2}\\ x=\dfrac{19}{7}-\dfrac{25}{2}\\ x=-\dfrac{137}{14}\)
`#3107.101107`
`4x = 5y => x/5 = y/4`
Đặt `x/5 = y/4 = k`
`=> x = 5k; y = 4k`
Ta có: `x^2 - y^2 = 1`
`=> (5k)^2 - (4k)^2 = 1`
`=> 25k^2 - 16k^2 = 1`
`=> 9k^2 = 1`
`=> k^2 = 1 \div 9`
`=> k^2 = 1/9`
`=> k^2 = (+-1/3)^2`
`=> k = +-1/3`
Với `k = 1/3`
`=> x = 1/3*5 = 5/3; y = 1/3*4 = 4/3`
Với `k = -1/3`
`=> x = -1/3*5 = -5/3; y = -1/3*4 = -4/3.`
\(10x-x=1\)
\(\Rightarrow10x-1x=1\)
\(\Rightarrow x\left(10-1\right)=1\)
\(\Rightarrow10-1=\frac{1}{x}\)
\(\Leftrightarrow9=\frac{1}{x}\)
\(\Leftrightarrow\frac{9}{1}=\frac{1}{x}\)
\(\Leftrightarrow9x=1\)
\(\Leftrightarrow x=\frac{1}{9}\)
\(\Leftrightarrow x=0,\left(1\right)\)
x= 10+1
x= 11