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=?
45*55+46*54+47*53+48*52+49*51=?
数学人气：187 ℃时间：2020-03-29 03:53:54
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