Question

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CMR: A= 2^100 + 2^ 101 + 2^ 102 + ......+2^107 chia het cho 3

Answer 1

[Trà My]

\(A=2^{100}+2^{101}+2^{102}+...+2^{107}\)

\(A=2^{100}\left(1+2\right)+2^{102}\left(1+2\right)+...+2^{106}\left(1+2\right)\)

\(A=2^{100}.3+2^{102}.3+...+2^{106}.3\)

\(A=3\left(2^{100}+2^{102}+...+2^{106}\right)⋮3\)