Question

If a1=9, a2=12, a3=17, a4=23, and a sigma notation with a 5 on the top and n=1 on the bottom with an=81 on the side, what is the value of a5

Answer 1

\[\sum_{n=1}^{5} an\]

Answer 2

So...\[\sum_{n=1}^{5}a _{n}=81\]?

Answer 3

yes

Answer 4

Ok.

\[\sum_{n=1}^{5}a _{n}\]is the same as\[a _{1}+a _{2}+a _{3}+a _{4}+a _{5}\]So you have\[a _{1}+a _{2}+a _{3}+a _{4}+a _{5}=81\]and\[a _{1}=9, a _{2}=12, a _{3}=17, a _{4}=23\]So\[9+12+17+23+a_{5}=81\]Can you take it from there?

Answer 5

yes thank you :)

Answer 6

:D