Question

Tính S=(-2)⁰+(-2)¹+ (-2)²+(-2)³+.......+(-2)²⁰¹⁴+(-2)²⁰¹⁵

Answer 1

S = (-2)^0 + (-2)^1 + (-2)^2 + (-2)^3+...+(-2)^2014+ (-2)^2015

S = 1 - 2 + 2^2 - 2^3 + ....+ 2^2014 - 2^2015

=> 2S = 2 - 2^2 + 2^3 - 2^4 + ....+ 2^2015 - 2^2016

=> 2S - S = 1 - 2^2016

\(S=1-2^{2016}\)

Answer 2

mk nhầm chỗ 2S - S phải là:

2S + S = 1 - 2^2016

=> \(S=\frac{1-2^{2016}}{3}\)