How do you use a graphing calculator to find the sum of the geometric series $Sigma 2(1/2)^(n-1)$ from n=1 to 15?

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Answer 1 · 2017-06-05T23:52:35

$S_{15} =4* (1 - 1/2^15) = 3.99987792968750000000$

$a_0 = 2 ; q = 1/2$

$a_{14} = 2/2^14 = 2^-13$

$S_n = a_0 * frac{1 - q^n}{1-q} = a_0 + a_0 q + ... + a_0 q^{n-1}$

$S_{15} = 2* frac{1 - 0.5^15}{1-0.5}$

How do you use a graphing calculator to find the sum of the geometric series Sigma 2(1/2)^(n-1)Sigma 2(1/2)^(n-1) from n=1 to 15?