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1. Let N= {…, -2, -1, 0, 1, 2 …} be the side of integers, positive negative and 0. A subgroup S of Z a nonempty subset with the property that if x and y are members of S, then so is x-y. Find all subgroups of Z that contain the integer 3. 2. Let N = 100…001 be the integer having n greater than or equal to 0 zero digits sandwiched etween the two ones. If N is a prime number, prove that n+1 is a power of 2. Please help! I don’t understand what is it asking… Thanks~_________________

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