Toán Lớp 6: Chứng minh rằng: A=1+3+3^2+3^3+…+3^2021 chia hết cho 10
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Toán Lớp 6: Chứng minh rằng: A=1+3+3^2+3^3+…+3^2021 chia hết cho 10
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A=(1+3+3^2+3^3)+……….+(3^2018+3^2019+3^2020+3^2021)
A=1.(1+3+3^2+3^3)+…………..+3^2018.(1+3+3^2+3^3)
A=1.40+……………+3^2018. 40
A=40.(1+…………+3^2018)
Vì 40vdots10
=>Avdots10