Question

Tính

2+\(2^2\)+\(2^3\)+........+\(2^{50}\)

Answer 1

\(Đặt\) \(A=\)\(2+2^2+2^3+.....+2^{50}\)

\(2A=2^2+2^3+2^4+......+2^{51}\)

\(2A-A=2^2+2^3+2^4+.....+2^{51}-2-2^2-2^3-......-2^{50}\)

\(A=\)\(2^{51}-2\)

Answer 2

A = 2 + 2² + 2³ + .. + 2⁵⁰

2A = 2² + 2³ + 2⁴ + ... + 2⁵¹

2A - A = 2⁵¹ - 2

A = 2⁵¹ - 1