( x+1 )4 = ( x+1 )2
( x+1 )4 - ( x+1 )2 = 0
( x+1 )2 . [ ( x+1 )2 - 1 ] = 0
\(\orbr{\begin{cases}\left(x+1\right)^2=0\\\left(x+1\right)^2-1=0\end{cases}}\Rightarrow\orbr{\begin{cases}x+1=0\\\left(x+1\right)^2=1\end{cases}}\)
\(\orbr{\begin{cases}s\\s\orbr{\begin{cases}s\\\end{cases}}\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x=-1\\x+1=1\text{ hoặc }x+1=-1\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-1\\x=0\text{ hoặc }x=-2\end{cases}}\)