Ta có:
3^n+2-2^n+2+3^n-2^n
=3^n+2+3^n-(2^n+2+2^n)
=3^n(3^2 +1)-2^n(2^2 +1)
=3^n.10-2^n.5=3^n.10-2^(n-1).10
=(3^n-2^(n-1)).10 chia het cho 10
Tick nhé
chung minh rang : voi moi so nguyen duong n thi :3n+2 -2n+2 +3n -2n chia het cho 10
chung minh rang voi moi N nguyen duong thi 3^n+2 - 2^n+2 + 3^n - 2^n chia het cho 10
CMR : \(3^{n+2}-2^{n+4}+3^n+2^2\)chia het cho 30 voi moi n nguyen duong
cmr voi moi son nguyen duong deu co A=5^n(5^n+1)-6^n(3^n+2)chia het cho 91
Chung minh rang: Voi moi so nguyen duong n thi: 3n+2 - 2n+2 + 3n - 2n chia het cho 10
GIUP MIK VS MOI NGUOI OI!
CMR voi moi n nguyen duong thi 3^n+2- 2^n+2+3^n- 2^n
chung minh rang: 3n+2 -2n+2 +3n -3n chia het cho 10 voi moi n nguyen duong
chung minh rang voi moi so nguyen duong n thi
10n + 18n -1 chia het cho 27
tim k sao cho 3^(6n-1)-k.3^(3n-2)+1 chia het cho 7 voi moi so nguyen duong n