Question

Use the first term (9) and tenth term (45) to find the sum of the first 10 terms. The sequence given is an=4n+5

Answer 1

\[S _{n}=\frac{n(a _{1}+a _{n})}{2}\]

Answer 2

Plug and chug.

Answer 3

uhh what do i plug in? :/ what's sn? and n like specifically what do i plug in :/

Answer 4

http://www.regentsprep.org/regents/math/algtrig/atp2/arithseq.htm