Toán Lớp 6: cho D = 3+ 3 mũ 2 + 3 mũ 3+ 3 mũ 4 chấm chấm chấm + 3 mũ 100 chứng tỏ D chia hết cho 40
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Toán Lớp 6: cho D = 3+ 3 mũ 2 + 3 mũ 3+ 3 mũ 4 chấm chấm chấm + 3 mũ 100 chứng tỏ D chia hết cho 40
Comments ( 1 )
A=(3+3^2+3^3+3^4)+(3^5+3^6+3^7+3^8)+…+(3^97+3^98+3^99+3^100)
A=3(1+3+3^2+3^3)+3^5(1+3+3^2+3^3)+….+3^97(1+3+3^2+3^3)
A=3.40+3^5.40+….+3^97.40
A=40.(3+3^5+…+3^97)chia hết cho 40
Vậy A chia hết cho 40