Question

a) Calculate the following (geometric) sums and series, respectively.
i) \(\Large \sum_{n=-2}^{10}2^{n}\)

Answer 1

so the series is \[\frac{1}{4} + \frac{1}{2} + 1 + 2 + 4 ....\]

a = 1/4 r = 2 and n = 10

then \[s _{n} = \frac{a(r^n - 1)}{r -1} \]

just substitute and the evaluate

Answer 2

oops n = 12 as you start at -2 and finish at 10

Answer 3

ok.. thank you @campbell_st