Page 119 - Numbertheory
P. 119
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27 n ()
2n +1
6( ) 5( ) 4( ) 3 ()
. 2n +1 : ()
. 2n +1∈{1, 3, 9, 27}
. n =0 27
2n +1
. n ∈{0,1, 4, 13}
. n ∈{1, 4, 13}
A −B B A [AMC10B 2002] ( )
: . A +B
()
3 () 7 ()
()
A +B A −B :( )
B A. 2
. A + B > A > A − B > 2 .( B A)
. B. A
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