a: Ta có: \(\sqrt[3]{x+1}=-5\)
\(\Leftrightarrow x+1=-125\)
hay x=-126
b: Ta có: \(\sqrt[3]{x+1}-1=x\)
\(\Leftrightarrow x+1=\left(x+1\right)^3\)
\(\Leftrightarrow\left(x+1\right)\left[\left(x+1\right)^2-1\right]=0\)
\(\Leftrightarrow x\left(x+1\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-1\\x=-2\end{matrix}\right.\)