Question

Find the 25th term of the arithmetic sequence whose common difference is d=5 and whose first term is a1 = 3 .

Answer 1

$\bf n^{th}\textit{ term of an arithmetic sequence} \\\\ a_n=a_1+(n-1)d\qquad \begin{cases} a_n=n^{th}\ term\\ n=\textit{term position}\\ a_1=\textit{first term}\\ d=\textit{common difference}\\[-0.5em] \hrulefill\\ a_1 = 3\\ d= 5\\ n = 25 \end{cases} \implies a_{25} = 3+(25-1)5 \\\\\\ a_{25} = 3+(24)5\implies a_{25} = 3+120\implies a_{25} = 123$