1、A certain list consists of several different integers. Is the product of all the integers in the list positive? 1)The product of the greatest and the smallest integers in the list is positive 2)There is an even number of integers in the list 答案是 C，为什么不是E呢？ -------------------------------------------------- 2、In the xy-plane, the line k passes through the origin and through the point (a,b), where ab≠0. Is b positive? 1)The slope of line k is negative 2)a<b 答案同样是 C，为什么不是E呢？
1、A certain list consists of several different integers. Is the product of all the integers in the list positive? 1)The product of the greatest and the smallest integers in the list is positive 2)There is an even number of integers in the list 答案是 C，为什么不是E呢？ ------------------------------------------- 最大数是L，最小数是S，LS>0,就是说最大最小数同号。 如果都是正数，那么product>0; 如果都是负数，那么只有当这个list有偶数个integers时product>0
2、In the xy-plane, the line k passes through the origin and through the point (a,b), where ab≠0. Is b positive? 1)The slope of line k is negative 2)a<b 斜率<0,line穿过原点，也就是说这条line是穿过第二，第四象限，第二象限的横坐标<0,纵坐标>0,也就是说a<0,b>0 第四象限横坐标>0,纵坐标<0,也就是说a>0,b<0.当a<b时，line穿过的是第二象限，可得b>0
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发表于 2010-9-30 20:35:14
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