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1E99

i just write it out ?

it says error

thats calculator for: 1x10^(99)

which model

TI - 84 plus

your comma button has an EE atop it, shift to get it

oh i see it now , hold up

Do you have a TI-89? These bad boys have an infinity BUTTON!! :D

oh no i have a 84 /:

@amistre64 it says EE but you said it was IE99

Same thing :)

it not my fault they cant type lol

Button likely says EE, but on screen it should say E

ok lemme try

the output on the screen is still:
one: 1
2nd, , : E
99: 99

is it a one or an I ?

they might have done that to distinguish it fromthe alpha E key :/

an i is not a real numerical value

"Imaginary"

i^k is one of 4 values ...
why are you needing an infinity?

hold up

\[\sum_{{j}={1}}^{\infty}4 \cdot 0.5^{j-1}\]

aha now what ? lol

is .5 less than 1?

theres a formula for this ....

yes

whats the formula ? im sorry my teacher doesnt give me all this info /:

\[\frac{1-r^k}{1-r}\]
if r < 1, then the limit as k to infinity is
\[\frac{1}{1-r}\]

whats r though ? the common ratio ?

but would it be possible to find the sum ?

if r < 1 then that exponented part goes to 0 leaving us:
S = r/(1-r) for the sum

might be better stated the |r| < 1, but why nitpick

\[\frac{4}{.5}\sum_{{j}={1}}^{\infty}0.5^{j}\]
\[\frac{4}{.5}~\frac{.5}{1-.5}\]
\[\frac{4}{.5}=8\]

http://www.wolframalpha.com/input/?i=sum+4%28.5%29%5E%28n-1%29%2C+n%3D1+to+inf

thanks soooo much !

youre welcome, as far as i know the ti84 does not have an infinite sum function

yes im aware haha