Tìm số tự nhiên n sao cho : 

a) ( n + 3 )  ⋮ ( n + 1 )

b) ( 2n + 6 ) ⋮ ( 2n - 6 )

c) ( 2n + 3 ) ⋮ ( n - 2 )

d) ( 3n + 2 ) ⋮ ( n - 3 )

giải nhanh và đầy đủ giùm mk nha

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