[tex]\bf \begin{array}{|l|ll} \cline{1-1} \cline{1-1} \\ i^4=1\\ i^2=-1 \\\\ \cline{1-1} \end{array}~\hspace{3.5em}5i^{10}\implies 5i^{4+4+2}\implies 5i^4i^4i^2\implies 5(1)(1)(-1)\implies -5[/tex]
