[toán 7] tìm số

N

nguyendanganh99

Trong phep chia cho 1000 co 1000 so du la 0,1,2,3...999.Xet 1001 so la 3, 3^2, 3^3... 3^1001 thi ton tai 2 so co cung so du trong phep chia cho 1000.
Goi 2 o do la 3^n va 3^m(1<=n<m<=1001) =>3^m-3^n Chia het cho 1000
=>3^n((3^m-n)-1)chia het cho 1000
ma (3^n,1000)=1
=3^(m-n)-1 chia het cho 1000 => 3^(m-n) tan cung la 001
 
N

nguyendanganh99

em co thi hoc sinh gioi huyen cung khong can chu y nam den nhung bai toan nhu the nay dau
 
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