Tìm x
a)13,6+x=79,5
b)4/x=1/20
c)x/100=123
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a) \(\dfrac{x+5}{4}-\dfrac{x}{2}+1=0\)
<=> \(\dfrac{x+5-2x+4}{4}=0\)
<=> -x + 9 = 0 <=> x = 9
b) \(3\left(x+2\right)=\dfrac{x-4}{3}\)
<=> 9x + 18 = x-4
<=> 8x = -22
<=> x = \(\dfrac{-11}{4}\)
\(a,\Leftrightarrow x^3-4x^2+4x=0\\ \Leftrightarrow x\left(x^2-4x+4\right)=0\\ \Leftrightarrow x\left(x-2\right)^2=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\end{matrix}\right.\\ b,\Leftrightarrow4\left(x-1\right)=3x+6\left(2x-3\right)\\ \Leftrightarrow4x-4=3x+12x-18\\ \Leftrightarrow11x=14\Leftrightarrow x=\dfrac{14}{11}\)
a/ \(x^3-4x^2=-4x\)
\(\Leftrightarrow x^3-4x^2+4x=0\)
\(\Leftrightarrow x\left(x^2-4x+4\right)=0\)
\(\Leftrightarrow x\left(x-2\right)^2=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\end{matrix}\right.\)
b/ \(\dfrac{x-1}{3}=\dfrac{x}{4}+\dfrac{2x-3}{2}\)
\(\Leftrightarrow8\left(x-1\right)=6x+12\left(2x-3\right)\)
\(\Leftrightarrow8x-8=6x+24x-36\)
\(\Leftrightarrow8x-8=30x-36\)
\(\Leftrightarrow8x-30x=8-36\)
\(\Leftrightarrow-22x=-28\)
\(\Leftrightarrow x=\dfrac{14}{11}\)
a, x=65,9
b, x=1/5=0,2
c,x=12300