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2 tháng 11 2025

ghép 3 số vào thì ra 1 số chia hết cho 13

sau đó ta phân tích ra giống như tổng ban đầu rồi dùng tính chất phân phối rồi sẽ ra 1 tích cos 13

2 tháng 11 2025

A=(3^1+3^2+3^3)+(3^4+3^5+3^6)+.........+(3^28+3^29+3^30)(có 10 nhóm)

=(3^1+3^2+3^3)+3^3x(3^1+3^2+3^3)+..............+3^27x(3^1+3^2+3^3)

=(3^1+3^2+3^3)x(1+3^3+...........+3^27)

=39x(1+3^3+...........+3^27)

=13x3x(1+3^3+...........+3^27) chia hết cho 13 (đccm)

tick nha

19 tháng 10 2017

\(A=3+3^2+3^3+...+3^{28}+3^{29}+3^{30}\)

\(A=\left(3+3^2\right)+\left(3^3+3^4\right)+...+\left(3^{29}+3^{30}\right)\)

\(A=1\left(3+3^2\right)+3^2\left(3+3^2\right)+....+3^{28}\left(3+3^2\right)\)

\(A=\left(1+3^2+...+3^{28}\right)\left(3+3^2\right)\)

\(A=13\left(1+3^2+...+3^{28}\right)⋮13\left(đpcm\right)\)

23 tháng 10 2015

TA CÓ:

A=30+3+32+33+........+311

(30+3+32+33)+....+(38+39+310+311)

3(0+1+3+32)+......+38(0+1+3+32

3.13+....+38.13 cHIA HẾT CHO 13 NÊN A CHIA HẾT CHO 13( đpcm)

 

4 tháng 8 2021
Fikj Hrtui
17 tháng 10 2017

a)\(2^{29}+2^{30}=2^{29}\left(1+2\right)=2^{29}.3⋮3\)

Vậy \(2^{29}+2^{30}⋮3\)

17 tháng 10 2017

B nữa bạn c luôn

27 tháng 12 2017

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28 tháng 12 2017

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29 tháng 12 2017

Câu 2:

\(C=3^{10}+3^{11}+3^{12}+...+3^{17}.\)

\(C=\left(3^{10}+3^{11}+3^{12}+3^{13}\right)+\left(3^{14}+3^{15}+3^{16}+3^{17}\right).\)

\(C=3^{10}\left(1+3+3^2+3^3\right)+3^{14}\left(1+3+3^2+3^3\right).\)

\(C=3^{10}\left(1+3+9+27\right)+3^{14}\left(1+3+9+27\right).\)

\(C=3^{10}.40+3^{14}.40.\)

\(C=\left(3^{10}+3^{14}\right).40⋮40\left(đpcm\right).\)

29 tháng 12 2017

\(C=3^{10}+3^{11}+..+3^{17}\\ =\left(3^{10}+3^{11}+3^{12}+3^{13}\right)+\left(3^{14}+..+3^{17}\right)\\ =3^{10}\left(1+3+3^2+3^3\right)+3^{14}\left(1+3+3^2+3^3\right)\\ =40\left(3^{10}+3^{14}\right)⋮40\)

31 tháng 12 2018

ta có:  A = 1 + 3 + 32 +...+ 329 ( có 30 chữ số)

A = (1+3+32) + ...+ (327+328+329) ( có 10 cặp)

A = 13 + ...+ 327.(1+3+32)

A = 13.(1+...+ 327) chia hết cho 13

2 tháng 10 2016

a) (1+5+52+53+...529)chia hết cho 6

Đặt (1+5+52+53+...529) = A

\(A=\left(1+5\right)+\left(5^2+5^3\right)+\left(5^4+5^5\right)....+\left(5^{28}+5^{29}\right)\)

\(A=\left(1+5\right)+5^2\left(5+1\right)+5^4\left(5+1\right)+...+5^{28}\left(5+1\right)\)

\(A=6+5^2.6+5^4.6+...+5^{28}.6\)

Vậy A chia hết cho 6

b) (1+3+3^2+3^3+...+3^29) chia hết cho 13

Đặt B= (1+3+3^2+3^3+...+3^29)

\(B=\left(1+3+3^2\right)+\left(3^3+3^4+3^5\right)+...+\left(3^{27}+3^{28}+3^{29}\right)\)

\(B=13+3^3\left(1+3+3^2\right)+....+3^{27}\left(1+3+3^2\right)\)

\(B=13+3^3.13+....+3^{27}.13\)

Vậy B chia hết 13

Câu c,d tương tự.Chúc bạn học tốt