If a1=a2=2,an=an-1-1(n>2),then a5is
1
-1
0
2
Find the value of a5:
Given that a1=a2=2,an=an-1-1(n>2),
an=an-1ā1........(i)
Put n=3 in the equation (i). we get
a3=a(3-1)ā1a3=a2ā1a3=2-1=1
Put n=4 in the equation (i). we get
a4=a(4-1)ā1a4=a3ā1a4=1ā1=0
Put n=5 in the equation (i). we get
a5=a(5-1)ā1a5=a4ā1a5=0ā1=-1
Hence, the correct option is ( B).