Let a=b (mod n) and c=d (mod n). Prove that ac=bd (mod n).?

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  • jibz
    Lv 6
    8 months ago

    By hypothesis there exist integers k and j such that

    a = b + kn,

    c = d + jn.

    So

    ac

    = (b + kn)(d + jn)

    = bd + bjn + knd + kjn²

    = bd + (bj + kd +kjn)·n

    = bd (mod n).

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