Question

using a graphing calculator, find the sum:
-1-2-4-8-...-(2^n-1)

Answer 1

I'm using a Ti-84 plus if that helps

Answer 2

i don't use any graph calculator but it is easy to calculate and plot
like it is an finite GP series :)

Answer 3

how so??

Answer 4

if i take -1 common then the series will become
now as sum of gp
where a is constant and r is the common ratio
so here a=1 and r=2
on putting sum=