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 i
问题描述：
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
答
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...