问题 填空题

设x6=a0+a1(x-1)+a2(x-1)2+a3(x-1)3+a4(x-1)4+a5(x-1)5+a6(x-1)6,则a3=______.

答案

∵x6=[(x-1)+1]6=

C06
+
C16
•(x-1)1+
C26
•(x-1)2+…+
C66
•(x-1)6

=a0+a1(x-1)+a2(x-1)2+a3(x-1)3+a4(x-1)4+a5(x-1)5+a6(x-1)6

∴a3=

C36
=20.

故答案为:20.

问答题
单项选择题