\(a,ĐK:x\ge\dfrac{5}{2}\\ PT\Leftrightarrow2x-5=4\Leftrightarrow x=\dfrac{9}{2}\left(tm\right)\\ b,PT\Leftrightarrow\left|x-3\right|=7\Leftrightarrow\left[{}\begin{matrix}x-3=7\\3-x=7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=10\\x=-4\end{matrix}\right.\\ c,ĐK:x\le4\\ PT\Leftrightarrow\left|x-8\right|=4-x\\ \Leftrightarrow\left[{}\begin{matrix}x-8=4-x\left(x\ge8\right)\\8-x=4-x\left(x\le8\right)\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x\in\varnothing\left(trái.vs.ĐK\right)\\0x=4\left(ktm\right)\end{matrix}\right.\Leftrightarrow x\in\varnothing\)
a) \(\sqrt{2x-5}=2\)
\(\Leftrightarrow\) \(\sqrt{2x-5}^2=2^2\)
\(\Leftrightarrow\) \(2x-5=4\)
\(\Leftrightarrow\) 2x = 9
\(\Leftrightarrow\) x = \(\dfrac{9}{2}\)
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