a)
(
-
1)
k
b
k
x
k
/a
k
+1
,
|
x
|
<
|
a/b
|
; °b)
(
-
1)
k
a
k
/
(
b
k
+1
x
k
+1
)
,
|
x
|
>
|
a/b
|
.