Page 15 - Numbertheory

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b (b divides a) a b b a

. a (divisor or factor)

:

. a c b c a b ()

. 3 18 6  18 3  6

. ac  bd cd ab ()

3× 5 = 15 . 3  6 5  10

. 6×10 = 60

36 . m≠0 ma  mb ab ( )

. 5×3  5×6

. −5  20 . a ≤ b b ≠0 ab ()

. 5 ≤ 20

2  − 2 −2  2 . a = ±b ba ab ( )

. 2 = −(−2)

. x ,y a  (bx + cy ) a  c a  b ()

3  15 3  6 . a  (b −c ) a  (b + c )

. 3  (2× 6 + 4×15)

p >1 (prime number)

.p 1

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