Question

tìm x biết
\(\sqrt{4-x}\)=x-2

Answer 1

ĐKXĐ: 4-x>=0

=>x<=4

\(\sqrt{4-x}=x-2\)

=>\(\left\{{}\begin{matrix}x-2>=0\\4-x=x^2-4x+4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2< =x< =4\\x^2-4x+4-4+x=0\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}2< =x< =4\\x^2-3x=0\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}2< =x< =4\\x\left(x-3\right)=0\end{matrix}\right.\)

=>x=3