Question

cho A= 1+2^1+2^2+...+2^100+2^101

Answer 1

$A=1+2^1+2^2+...+2^{101}$

$2A=2+2^2+2^3+...+2^{101}+2^{102}$.

Vậy $2A-A=(2+2^2+2^3+...+2^{101}+2^{102})-(1+2^1+2^2+...+2^{101})$

$\rightarrow$$A=2^{102}-1$.

Answer 2

2A=2+2^2+2^3+...+2^102

=>A=2^102-1

Answer 3

trả lời chi tiết ra giúp mink với nhé