a-2a+3a-4a+5a-6a+7a-8a+9a-10a+11a.+99a-100a=
问题描述:
a-2a+3a-4a+5a-6a+7a-8a+9a-10a+11a.+99a-100a=
答
-a×50=-50a
答
-50a
原式=(a-2a)+(3a-4a)+……(99a-100a)=-50a