问题 选择题

(x-1)5+5(x-1)4+10(x-1)3+10(x-1)2+5(x-1)等于(  )

A.x5-1

B.x5

C.x5+1

D.(x-1)5-1

答案

原式=C50(x-1)5+C51(x-1)4+C52(x-1)3+C53(x-1)2+C54(x-1)+C55-1

=[1+(x-1)]5-1=x5-1

故选A.

问答题
单项选择题