问题
选择题
若
|
答案
∵a=lim x→1
=x2-6x+5 x2-1 lim x→1
=(x-1)(x-5) (x-1)(x+1) lim x→1
=-2．x-5 x+1
∴
(lim n→∞
+1 a
+1 a2
+…+1 a3
)=1 an
[(-lim n→∞
)+(-1 2
)2+(-1 2
)3+…+(-1 2
)n]1 2
=lim n→∞
=-(-
)× [1-(-1 2
)n]1 2 1+ 1 2
．1 3
故选B．