Question

🐎

最後一行不懂為什麼 感恩大家🙏

an1
On-l + On-2 , n23,
100
-
in In=1
| adj =1,
, =
說例6 設數列{a, 之定義為 a
說例
) 2
an
漂亮題
az = 2 ' * lim a, = ?
2.
n
n->00
[解]解此題需用“對消”觀念!由
1
C.
=(an-1 +an-2), n23
2
=
F2

---
azt
1=3 ? 2x = a2 + a
n,
-
+4' )
244 = 2 + a2
20 =
-
de
+
n=5,
2 ant+lant ant.
= 2ant ant
+
+ an3
des
十次
(S
n
n=n-1'2an-1 = cm2
n=n’ 2a, = An-1 + 2
1870F 22+an+1 = a2 + a, +az = 2+1+2=5
,
map = lim a. = 4,代入上式得 34=5,故A==
= A · ALEI =
=
+1+25
5
o
lim
an
二
n00
'n-1
3
n->00