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Cho x,y thuộc n thoả mãn x hia 3 dư 1,y chia 3 dư 2.hỏi x.y chia 3 có số dư bằng bao nhiêu

1 Answer

4 votes

Answer:

2

Explanation:

x÷3 dư 1-->x=3a+1

y÷3 dư 2-->y=3b+2

x×y=(3a+1)×(3b+2)

=9ab+6a+3b+2

Mà 9ab, 6a, 3b chia hết cho 3, 2 chia 3 dư 1

==>x×y chia 3 dư 2

User Johan Leino
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