Question

Consider the series 4 + 12 + 36 ... Find the sum of the first 9 terms.​

Answer 1

39364

Explanation:

You can simplify the equation to make 4(1+3+9...) The nth term is therefore
`3^(n-1)` so u can substitute that into the equation so 4(
`3^(n-1)+ 3^(n) + 3^(n+1)`..). This would simplify to 4(
`3^0 +3+3^2`+
`3^3+3^4+3^5+3^6+3^7+3^8`). By simplifying this, you can make it so 4(
`2^2+6^2+18^2+42^2+81^2`) = 4(4+36+324+2916+6561) =39364