化简下列各数的符号
问题描述:
化简下列各数的符号
-{+[-(2a-1)]} +{-[-(x-y)]}
答
-{+[-(2a-1)]}
=-[-(2a-1)]
=+ (2a-1)
=+2a-1
+{-[-(x-y)]}
=-[-(x-y)]
=+(x-y)
=+x-y