Question

 

的相反數(shù)是-2.1；-3的絕對(duì)值是

 

；|-

1

2

|的倒數(shù)是

 

．

Answer 1

分析：利用相反數(shù)，絕對(duì)值，倒數(shù)的概念及性質(zhì)做題．

解答：解：相反數(shù)是-2.1的數(shù)為2.1；-3的絕對(duì)值是3；|-

1

2

|=

1

2

的倒數(shù)是2．

點(diǎn)評(píng)：主要考查相反數(shù)，絕對(duì)值，倒數(shù)的概念及性質(zhì)．
相反數(shù)的定義：只有符號(hào)不同的兩個(gè)數(shù)互為相反數(shù)，0的相反數(shù)是0；
倒數(shù)的定義：若兩個(gè)數(shù)的乘積是1，我們就稱這兩個(gè)數(shù)互為倒數(shù)．
絕對(duì)值規(guī)律總結(jié)：一個(gè)正數(shù)的絕對(duì)值是它本身；一個(gè)負(fù)數(shù)的絕對(duì)值是它的相反數(shù)；0的絕對(duì)值是0．