0和任何数相乘得 ．1和任何数相乘都得 ．
÷=； ÷=．
因为A×B=1，所以A=，B=．（A、B≠0） ．
÷7=÷ =38．
× =× = ×= ×0.1=+ = ﹣．
× =× =+ =1.5× =× =1．
，B=
．（A、B≠0） ．
=
； ÷
=
．
÷ =38．
× =
× = ×
= ×0.1=
+ = ﹣
× =
× =
+ =1.5× =
× =1．
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