4555+4654+4753+4852+49*51=?

分类: 作业答案 • 2021-12-28 14:33:57

问题描述：

45*55+46*54+47*53+48*52+49*51=?

答

45*55+46*54+47*53+48*52+49*51=
=(50-5)(50+5)+(50-4)(50+4)+(50-3)(50+3)+(50-2)(50+2)+(50-1)(50+1)
=2500*5-25-16-9-4-1
=12500-55
=12445

45*55+46*54+47*53+48*52+49*51=?