По теореме Виета:
\end{gathered}\right.\\2) x^4+3x^2-4=0\\ t=x^2, t\geq0\\ t^2+3t-4=0\\ \left [ \begin{gathered} t=-4 \notin t\geq0\\ t=1 \end{gathered}\right.\\ x^2=1\\ x=\pm1\\ " alt="\left [
\begin{gathered} x=-8\\x=3
\end{gathered}\right.\\2) x^4+3x^2-4=0\\ t=x^2, t\geq0\\ t^2+3t-4=0\\ \left [ \begin{gathered} t=-4 \notin t\geq0\\ t=1 \end{gathered}\right.\\ x^2=1\\ x=\pm1\\ " align="absmiddle" class="latex-formula">
Ответ: В