Question

Cho A=1+2+2²+...+2²⁰¹⁴+2²⁰¹⁵

B=2²⁰¹⁶-1

So sánh A và B

 

 

Answer 1

2A = 2 + \(2^2+2^4+2^5+..........+2^{2015}+2^{2016}\)

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

vậy B = A

ủng hộ nha ai thấy đúng

Answer 2

\(A=1+2+2^2+...+2^{2015}\)

\(2A=2+2^2+2^3+...+2^{2016}\)

\(2A-A=\left(2+2^2+2^3+...+2^{2016}\right)-\left(1+2+2^2+...+2^{2015}\right)\)

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

Vậy \(A=B=2^{2016}-1\)