Question

\(\text{Cho : A = 1 + }2+2^2+2^3+...+2^9\)

\(\text{Hãy so sánh A với }5.2^8\)

Answer 1

\(2A=2+2^2+...+2^{10}\)

\(2A-A=\left(2+2^2+...+2^{10}\right)-\left(1+2+...+2^9\right)\)

\(A=2^{10}-1=1023\)

mà \(5\cdot2^8=1280\Rightarrow A< 5\cdot2^8\)

Answer 2

A = 1 + 2+22+23+...+29

2A = 2 + \(2^2+2^3+2^4+...+2^{10}\)

\(-\)

 \(A=1+2+2^2+2^3+...+2^9\)

 \(A=\)\(1-2^{10}\)

KL= tự so sánh nha

Answer 3

à mình sorry nha phải là \(2^{10}-1\)mới mình so sánh hộ luôn

\(2^{10}-1=1023\)

\(5.2^8=1280\)

Vì 1280 > 1023 \(\Rightarrow A< 5.2^8\)