Question

3.( a - 2a )² = 27

Answer 1

\(3\left(a-2a\right)^2=27\Leftrightarrow3\left(-a\right)^2=27\Leftrightarrow\left(-a\right)^2=\dfrac{27}{3}=9\)

\(\Leftrightarrow\left\{{}\begin{matrix}-a=3\\-a=-3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=-3\\a=3\end{matrix}\right.\) vậy \(x=3;x=-3\)

Answer 2

3 . ( a - 2a )² = 27

3 . ( -a )² = 27

3 . a = 27

a = 9