Question

(x-3)²   - 4x² = 0

 

Answer 1

(x-3)² - 4x² = 0

( x-3 - 2x)( x-3 +2x) =0

(-x-3)(3x-3)=0

\(\left[{}\begin{matrix}-x-3=0\\3x-3=0\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=-3\\3x=3\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=-3\\x=3:3\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=-3\\x=1\end{matrix}\right.\)

Kết luận x \(\in\) { -3;1}

 

Answer 2

(x-3)²-4x²=0

(x-3-2x)(x-3+2x)=0

⇒\(\left\{{}\begin{matrix}x-3-2x=0\\x-3+2x=0\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}-x-3=0\\3x-3=0\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=-3\\x=1\end{matrix}\right.\)