Ta có : 3^n+2 - 2^n+4 + 3^n + 2^n
= (3^n+2 + 3^n) - (2^n+4-2^n)
= 3^n-1.(3^3+3) - 2^n-1.(2^5-2) ( vì n nguyên dương nên n-1 >= 0 )
= 3^n-1.30 - 2^n-1.30
= 30.(3^n-1+2^n-1) chia hết cho 30
=> ĐPCM
Tk mk nha
CMR voi moi so nguyen duong n thi B=3^n+2 -2^n+2 +3^n -2^n chia het cho 10
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 N nguyen duong thi 3^n+2 - 2^n+2 + 3^n - 2^n chia het cho 10
chung minh rang : voi moi so nguyen duong n thi :3n+2 -2n+2 +3n -2n chia het cho 10
chung minh rang: 3n+2 -2n+2 +3n -3n chia het cho 10 voi moi n nguyen duong
tim k sao cho 3^(6n-1)-k.3^(3n-2)+1 chia het cho 7 voi moi so nguyen duong n
chung minh rang voi moi n nguyen duong ta luon co
4^n+3+4^n+2-4^n+1-4^nchia het cho 300
CMR voi moi n nguyen duong thi 3^n+2- 2^n+2+3^n- 2^n
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!
