a) \(\sqrt{16x-32}+\sqrt{25x-50}=18+\sqrt{9x-18}\left(đk:x\ge2\right)\)
\(\sqrt{9\left(x-2\right)}+18-\sqrt{16\left(x-2\right)}-\sqrt{25\left(x-2\right)}=0\)
\(3\sqrt{x-2}-4\sqrt{x-2}-5\sqrt{x-2}+18=0\)
\(18-6\sqrt{x-2}=0\)
\(3=\sqrt{x-2}\)
\(x-2=9\)
\(x=11\)
b) \(\left|7x-9\right|+1=x-3\)
\(\left|7x-9\right|=x-4\)\(\left(đk:x\ge4\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}7x-9=x-4\\7x-9=-x+4\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}6x=5\\8x=13\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{6}\\x=\dfrac{13}{8}\end{matrix}\right.\)
c) \(\sqrt{4x-5}=x+2\left(đk:x\ge\dfrac{5}{4}\right)\)
\(4x-5=\left(x+2\right)^2\)
\(x^2+4x+4=4x-5\)
\(x^2+9=0\) (vô lý vì \(x^2\ge0\forall x\))
