A = 2 + 2² + 2³ + 2⁴ + ... +  2¹⁰

A = 2¹ . (1 + 2) + 2³ . (1 + 2) + ... + 2⁹ + (1 + 2 )

A = 2¹ . 3 + 2³  . 3 + ... + 2⁹ . 3

A = 3 . (2¹ + 2³ + ... + 2⁹)

Vậy A chia hết cho 3

A=2+2^2+...+2^10=2(1+2)+2^3(1+2)+...+2^9(1+2)=2*3+2^3*3+2^9*3=(2+2^3+...+2^9)*3=> CHIA HẾT CHO 3

Ta có

\(A=2+2^2+2^3+...+2^{10}=\left(2+2^2\right)+\left(2^3+2^4\right)+...+\left(2^9+2^{10}\right)\)

\(A=2.3+2^3.3+...+2^9.3=3\left(2+2^3+...+2^9\right)\)

=>A chia hết cho 3

câu này dễ mà bạn

IB

Ta có: \(A=2+2^2+2^3+...+2^{10}\)

\(\Leftrightarrow A=\left(2+2^2\right)+\left(2^3+2^4\right)+..+\left(2^9+2^{10}\right)\)

\(\Leftrightarrow A=6+2^2\left(2+2^2\right)+..+2^8\left(2+2^2\right)\)

\(\Leftrightarrow A=6+2^2.6+...+2^8.6\)

\(\Leftrightarrow A=6\left(1+2^2+...+2^8\right)\)

Vì \(6⋮3\)

\(\Rightarrow A=6\left(1+2^2+..+2^8\right)⋮3\)

Vậy \(A⋮3\)

hok tốt !!!

\(A=2+2^2+2^3+...+2^{10}\)

\(\Leftrightarrow A=\left(2+2^2\right)+\left(2^3+2^4\right)+...+\left(2^9+2^{10}\right)\)

\(\Leftrightarrow A=2\left(1+2\right)+2^3\left(1+2\right)+....+2^9\left(1+2\right)\)

\(\Leftrightarrow A=2\cdot3+2^3\cdot3+....+2^9\cdot3\)

\(\Leftrightarrow A=3\left(2+2^3+....+2^9\right)\)

=> A chia hết cho 3

 A=2+2².2³⁺.....+ 2¹⁰

=> A= (2+2²) +(2³ +2⁴) +....+(2⁹ + 2¹⁰)

=> A=2 x (1+2¹) + 2³ x (1 + 2¹) +...+2⁹ x(1+2¹ )

=> A = 2 X 3 + 2³ X 3 +...+2⁹ X 3

=> A=3 x (2 + 2³+...+2⁹)

 Vậy A chia hết cho 3

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