\(b,\left(5+x\right)^2-36=0\\ =>\left(5+x\right)^2=36\\ =>\left[{}\begin{matrix}5+x=6\\5+x=-6\end{matrix}\right.\\ =>\left[{}\begin{matrix}x=1\\x=-11\end{matrix}\right.\)
`(5+x)^2-36=0`
`=>(5+x)^2=0+36`
`=>(5+x)^2=36`
`=>(5+x)^2=6^2` hoặc `(-6)^2`
`@TH1:`
`=>5+x=6`
`=>x=6-5`
`=>x=1`
`@TH2:`
`=>5+x=-6`
`=>x=-6-5`
`=>x=-11`
Vậy `x in{1;-11}`