Đk: x >/ 5
pt đã cho \(\Leftrightarrow7\sqrt{x-2}-14\cdot\dfrac{\sqrt{x-2}}{7}-3\sqrt{x-5}=4\)
\(\Leftrightarrow7\sqrt{x-2}-2\sqrt{x-2}-3\sqrt{x-5}=4\)
\(\Leftrightarrow5\sqrt{x-2}-3\sqrt{x-5}=4\)
\(\Leftrightarrow5\sqrt{x-2}=4+3\sqrt{x-5}\)
\(\Leftrightarrow25x-50=16+9x-45+24\sqrt{x-5}\)
\(\Leftrightarrow16x-21=24\sqrt{x-5}\)
\(\Leftrightarrow\left\{{}\begin{matrix}256x^2-672x+441=576x-2880\\x\ge\dfrac{21}{16}\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}256x^2-1248x+3321=0\\x\ge\dfrac{21}{16}\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}256x^2-1248x+3321=0\left(vn\right)\\x\ge\dfrac{21}{16}\end{matrix}\right.\)
Kl: ptvn
