Question

Find the sum of the first 40 terms of the series -1+1+5+13+....​

Answer 1

2^41-122

Explanation:

-120 in total as each term is 3 less than a power of 2

Starts at power of 1 will end on 40

adding consecutive powers will give 2 less than the next power

2^(40+1)-120-2

2^41-122