题文

计算：（每小题6分，共24分） (1)    (2)    (3)    (4)

题型：解答题  难度：中档

答案

（1） （2）-16 （3）-49 （4）-19

(1) 解：原式····································································· 1分 ································································ 2分 ··········································································· 4分 ·················································································· 6分 (2) 解：原式························································· 1分 ······························································ 4分 ·········································································· 5分 ················································································ 6分 (3) 解：原式·························································· 3分 ······································································ 4分 ················································································ 6分 (4) 解：原式···················································· 2分 ······························································ 3分 ····································································· 4分 ··········································································· 5分 ··············································································· 6分

据专家权威分析，试题“计算：（每小题6分，共24分）(1)(2)(3)(4)-七年级数学-”主要考查你对  有理数定义及分类，正数与负数，数轴，相反数  等考点的理解。关于这些考点的“档案”如下：

有理数定义及分类正数与负数数轴相反数

考点名称：有理数定义及分类

• 有理数的定义：
  有理数是整数和分数的统称，一切有理数都可以化成分数的形式。

• 有理数的分类：
  （1）按有理数的定义：
                                正整数 
                   整数{     零 
                                负整数
  有理数{     
                              正分数 
                  分数{
                              负分数
   
  
  （2）按有理数的性质分类: 
                             正整数  
                 正数{ 
                             正分数
  有理数{  零
                             负整数 
                 负数{
                             负分数

考点名称：正数与负数

• 正数：
  就是大于0的（实数）
  负数：
  就是小于0的（实数）
  0既不是正数也不是负数。

  非负数：正数与零的统称。
  非正数：负数与零的统称。

• 正负数的认识：
  1.对于正数和负数的概念，不能简单的理解为：带“＋”号的数是正数，带“－”号的数是负数。
  例如：-a一定是负数吗？
  答案是不一定，因为字母a可以表示任意的数。
  若a表示正数时，-a是负数；
  当a表示0时，-a就是在0的前面加一个负号，仍是0，0不分正负；
  当a表示负数时，-a就不是负数了，它是一个正数。

  2.引入负数后，数的范围扩大为有理数，奇数和偶数的外延也由自然数扩大为整数，整数也可以分为奇数和偶数两类，能被2整除的数是偶数，
  如…－6，－4，－2，0，2，4，6…，不能被2整除的数是奇数，如…－5，－4，－2，1，3，5…