Toán Lớp 6: Điền vào chỗ chấm 3^1;3^2;3^3;…;3^60 chia hết cho 13
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Toán Lớp 6: Điền vào chỗ chấm 3^1;3^2;3^3;…;3^60 chia hết cho 13
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Đặt A
A=3^1+3^2+3^3+…………+3^60
A=(3^1+3^2+3^3)+……………..+(3^58+3^59+3^60)
A=1.(3^1+3^2+3^3)+……………+3^57.(3^1+3^2+3^3)
A=1.39+…………….+3^57. 39
A=39.(1+………….+3^57)
Vì 39vdots13
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