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题目
1. If x and y are integers and xy+x^2 is oddh which of the following statements must be true?① x is odd② y is odd③ x+y is oddA. ①B. ③C. ① and ②D. ① and ③E. ② and ③2. For how many integers n is (2n+1)(3n-1) a negative number?A. NoneB. OneC. TwoD. ThreeE. Four求详解

提问时间:2021-01-25

答案
1、x和y都是整数,“xy+x^2是奇数”就是说:x*(x+y)是奇数.我觉得这道题问的是哪种组合是正确的.因为单独看,①②③都是推不出来的【也就是说A和B不对】,如果x是奇数,y也是奇数,那么x+y成了偶数,x*(x+y)也就成了偶数...
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