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\(\left(\dfrac{1}{2}\right)^x+\left(\dfrac{1}{2}\right)^{x+2}=\dfrac{1}{128}\\ \left(\dfrac{1}{2}\right)^x.\left[1+\left(\dfrac{1}{2}\right)^2\right]=\dfrac{1}{128}\\ \left(\dfrac{1}{2}\right)^x.\dfrac{5}{4}=\dfrac{1}{128}\\ \left(\dfrac{1}{2}\right)^x=\dfrac{1}{128}:\dfrac{5}{4}=\dfrac{1}{128}.\dfrac{4}{5}=\dfrac{4}{640}=\dfrac{1}{160}\)
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`#3107.101107`
\(\left(\dfrac{1}{2}\right)^x+\left(\dfrac{1}{2}\right)^{x+2}=\dfrac{1}{128}\)
\(\Rightarrow\left(\dfrac{1}{2}\right)^x\cdot\left[1+\left(\dfrac{1}{2}\right)^2\right]=\dfrac{1}{128}\)
\(\Rightarrow\left(\dfrac{1}{2}\right)^x\cdot\left(1+\dfrac{1}{4}\right)=\dfrac{1}{128}\)
\(\Rightarrow\left(\dfrac{1}{2}\right)^x\cdot\dfrac{5}{4}=\dfrac{1}{128}\)
\(\Rightarrow\left(\dfrac{1}{2}\right)^x=\dfrac{1}{128}\div\dfrac{5}{4}\)
\(\Rightarrow\left(\dfrac{1}{2}\right)^x=\dfrac{1}{160}\)
Bạn xem lại đề.
Ta có: \(\left\{{}\begin{matrix}\left|0,25x-1\right|\ge0\forall x\\\left|3-2y\right|\ge0\forall y\end{matrix}\right.\)
\(\Rightarrow\left|0,25x-1\right|+\left|3-2y\right|\ge0\forall x,y\)
Mà: \(\left|0,25x-1\right|+\left|3-2y\right|=0\)
nên: \(\left\{{}\begin{matrix}0,25x-1=0\\3-2y=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}0,25x=1\\2y=3\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x=4\\y=\dfrac{3}{2}\end{matrix}\right.\)
Vậy: \(x=4;y=\dfrac{3}{2}\).
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