1:正数集合:﹛15,0.15,22/5,+20,。。。﹜
负数集合:﹛-3/8,-30,-12.8,-60。。。﹜
2:-4的相反数是4
+2的相反数是的-2
-1.5相反数是1.5
0相反数是0
1/3的相反数是-1/3
-9/4的相反数是9/4