【導(dǎo)讀】+7,-2,31,-83,0,+001,-52,121,哪些是正數(shù)?畫一條數(shù)軸,并在數(shù)軸上標(biāo)出下列各數(shù):?,F(xiàn)在我們撇開例題的實(shí)際意義來研究有理數(shù)的絕對(duì)值,那么,+5的絕對(duì)值是5,在數(shù)軸上表示+5的點(diǎn)到原點(diǎn)的距離是5;一個(gè)負(fù)數(shù)的絕對(duì)值是它的相反數(shù);這也是絕對(duì)值的代數(shù)定義?-21的符號(hào)是____,絕對(duì)值是______;10-5的符號(hào)是_____,絕對(duì)值是______