1: ĐKXĐ: x>=5/2
\(x-\sqrt{2x-5}=4\)
=>\(\sqrt{2x-5}=x-4\)
=>\(\left\{{}\begin{matrix}x-4>=0\\\left(x-4\right)^2=2x-5\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x>=4\\x^2-8x+16-2x+5=0\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x>=4\\x^2-10x+21=0\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x>=4\\\left(x-3\right)\left(x-7\right)=0\end{matrix}\right.\)
=>x=7
2: ĐKXĐ: x>=1
\(\sqrt{x-1}=x-3\)
=>\(\left\{{}\begin{matrix}x-3>=0\\\left(x-3\right)^2=x-1\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x>=3\\x^2-6x+9-x+1=0\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x>=3\\x^2-7x+10=0\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x>=3\\\left(x-2\right)\left(x-5\right)=0\end{matrix}\right.\)
=>\(x=5\)
\(x-\sqrt{2x-5}=4\) đúng ko em?
Còn câu dưới là: \(\sqrt{x-1}=x-3\)?
