[tex]n^{th}\textit{ term of a geometric sequence} \\\\ a_n=a_1\cdot r^{n-1}\qquad \begin{cases} a_n=n^{th}\ term\\ n=\stackrel{\textit{term position}}{4}\\ a_1=\stackrel{\textit{first term}}{10}\\ r=\stackrel{\textit{common ratio}}{10} \end{cases} \\\\\\ a_4=10\cdot 10^{4-1}\implies a_4=10\cdot 1000\implies a_4=10000[/tex]
