Question

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

Answer 1

Answer:

39364

Step-by-step 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