法一:∵a2-3a-1=0,
∴(a?
) 2? 3 2
=0,13 4
∴a-
=±3 2
,
13
2
∴a=
,3±
13
2
当a=
时,a3-10a=3+
13
2
×3+
13
2
=33
?9
13
2
当a=
时,a3-10a=3?
13
2
×3?
13
2
=3;?3
?9
13
2
法二:∵a2-3a-1=0,∴a2-1=3a,a2-3a=1,
则a3-10a=a3-9a-a=a3-3(a2-1)-a
=a3-3a2+3-a=a(a2-3a)+3-a=a+3-a=3.
故答案为:3
a3-10a=a3-3a2+3a2-9a-a=a+3-a=3