Question

Tìm X : \(\sqrt{4\text{X}^2-20\text{X}+25}=1\)

Answer 1

\(\sqrt{4X^2-20X+25}=1\Leftrightarrow\sqrt{\left(2X\right)^2-2.2X.5+5^2}=1\Leftrightarrow\sqrt{\left(2X-5\right)^2}=1\Leftrightarrow\left|2X-5\right|=1\Leftrightarrow\)\(\left[{}\begin{matrix}2X-5=1\\2X-5=-1\end{matrix}\right.\)\(\Leftrightarrow\)\(\left[{}\begin{matrix}2X=6\\2X=4\end{matrix}\right.\)\(\Leftrightarrow\)\(\left[{}\begin{matrix}X=3\\X=2\end{matrix}\right.\)

Vậy S={2;3}