Question

Answer 1

\(\dfrac{x+2}{3}=\dfrac{3}{x+2}\)

\(\Leftrightarrow\left(x+2\right)^2=9\)

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

\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-5\end{matrix}\right.\)

Answer 2

\(\Leftrightarrow\left(x+2\right)^2=9\)

=>x+2=3 hoặc x+2=-3

=>x=1 hoặc x=-5

Answer 3

=>\(\left(x+2\right)^2=9\)

=>\(\left[{}\begin{matrix}x+2=3\\x+2=-3\end{matrix}\right.=>\left[{}\begin{matrix}x=1\\x=-5\end{matrix}\right.\)

Answer 4

e) \(\dfrac{x+2}{3}=\dfrac{3}{x+2}\)

\(\Rightarrow\left(x+2\right)^2=9\)

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

\(\Rightarrow\left[{}\begin{matrix}x=1\\x=-5\end{matrix}\right.\)

Vậy: \(x\in\left\{1;-5\right\}\)

Answer 5

\(e,\Leftrightarrow\left(x+2\right).\left(x+2\right)=3.3\)

\(\Rightarrow\left(x+2\right)^2=9=3^2=\left(-3\right)^2\)

\(\Leftrightarrow\left\{{}\begin{matrix}x+2=3\\x+2=-3\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=1\\x=-5\end{matrix}\right.\)