Question

A=14+3+3²+3³+...+3⁹⁷+3⁹⁸.Chứng minh rằng A chia hết cho 13

Answer 1

\(A=13+(1+3+3^{2})+3^{3}(1+3+3^{2})+...+3^{96}(1+3+3^{2})\)

\(A=13+13+3^{3}.13+...+3^{96}.13\)

\(A=13(1+1+...+3^{96})\vdots 13\)

Answer 2

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