Question

Answer 1

\(x^2\left(x^2+1\right)-x^2-1=0\)

\(\Leftrightarrow x^2\left(x^2+1\right)-\left(x^2+1\right)=0\)

\(\Leftrightarrow\left(x^2-1\right)\left(x^2+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2=1\\x^2=-1\left(vn\right)\end{matrix}\right.\)

\(\Rightarrow x=\pm1\)