`15 + (x+2)^2 : 3 = 18`
`=> (x+2)^2 : 3 = 18 -15`
`=> (x+2)^2 : 3 = 3`
`=> (x+2)^2 = 3^2`
`=> x + 2 = -3` hoặc x` + 2 = 3`
`=> x = -5` hoặc `x = 1`
Vậy ...
\(15+\left(x+2\right)^2:3=18\)
\(\left(x+2\right)^2:3=18-15\)
\(\left(x+2\right)^2:3=3\)
\(\left(x+2\right)^2=3\times3\)
\(\left(x+2\right)^2=9\)
\(\left(x+2\right)^2=3^2\) hoặc \(\left(x+2\right)^2=\left(-3\right)^2\)
\(x+2=3\) hoặc \(x+2=-3\)
\(x=3-2\) hoặc \(x=-3-2\)
\(x=1\) hoặc \(x=-5\)
Vậy ........