Question

Find the sum of the first 15 terms of an ap whose 1st and last term are -4 and 46 respectively?

Answer 1

#1, ok
#2, no
first year --- 8 = 8*2^0
2nd year --- 16 = 8*2^1
3rd year --- 32 = 8*2^2
...
6th year ---- ??

#3 >>>