Does the integer k have at least three different positive prime factors? (1) K/ 15 is an integer (2) K/ 10 is an integer.

The answer is C. The two statements together are subordinate, but the internal statement 1 is subordinate.

The explanation given in the book is that the (1) prime factors of 15 are 3 and 5, so in this case, k has at least two different positive prime factors, but whether there are more positive prime factors is unknown; Not satisfied. Similarly, (2) has at least two positive prime factors, 2 and 5. And (1)+(2) must be divisible by 2, 3 and 5. So the answer is C.

But the landlord's confusion is whether the integer k is a positive integer. In the case of (1)+(2), it is possible that k= -30, k/ 15 and k/ 10 are all negative integers (negative integers are also integers ... the landlord is entangled with ORZ at this point), so the prime factor of k may be -2. . . Help enthusiastic friends save lives ... QAQ

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