\(\left(x+5\right)^2=9\\ =>\left[{}\begin{matrix}\left(x+5\right)^2=3^2\\\left(x+5\right)^2=\left(-3\right)^2\end{matrix}\right.=>\left[{}\begin{matrix}x+5=3\\x+5=-3\end{matrix}\right.=>\left[{}\begin{matrix}x=-2\\x=-8\end{matrix}\right.\)
Vậy \(x=-2;x=-8\)
`(x+5)^2=9`
`=>(x+5)^2=3^2=(-3)^2`
`@TH1:`
`x+5=3`
`=>x=3-5`
`=>x=-2`
`@TH2:`
`x+5=-3`
`=>x=-3-5`
`=>x=-8`
(x+5)2=9
<=>\(\left\{{}\begin{matrix}x+5=3\\x+5=-3\end{matrix}\right.\)
<=>\(\left\{{}\begin{matrix}x=3-5=-2\\x=-3-5=-8\end{matrix}\right.\)
Vậy x∈{-2;-8}