Test Index

NCERT Class XI Mathematics - Sequences and Series - Solutions

© examsnet.com
Question : 14
Total: 106
The Fibonacci sequence is defined by 1 = a1 = a2 and an = an−1+an−2 , n > 2.
Find
an+1
an
 , for n = 1 , 2 , 3 , 4 , 5.
Solution:  
We have, a1 = 1 , a2 = 1 , a3 = a2+a1 = 1 + 1 = 2
a4 = a3+a2 = 2 + 1 = 3 , a5 = a4+a3 = 3 + 2 = 5 , a6 = a5+a4 = 5 + 3 = 8
Now, substitute n = 1, 2, 3, 4, 5 in
an+1
an
 , we obtain
a2
a1
 =
1
1
 = 1 ,
a3
a2
 =
2
1
 = 2,
a4
a3
 =
3
2
 ,
a5
a4
 =
5
3
 ,
a6
a5
 =
8
5
.
© examsnet.com
Go to Question:
Prev Question
Next Question