Given the expression
32n+2−8n−9, we want to determine the maximum power of 2 that divides this expression for all
n∈N.
First, we can rewrite
32n+2 as
9n+1 :
9n+1−8n−9Considering
9=1+8, we can apply the binomial expansion to
(1+8)n+1 :
(1+8)n+1=n+1C0+n+1C1⋅8+n+1C2⋅82+n+1C3⋅83+⋯Simplifying, we get:
1+8(n+1)+82n+1C2+n+1C3⋅83+⋯Subtracting
8n+9 from this sequence, we have:
1+8n+8+82n+1C2+⋯−8n−9Which simplifies to:
82(n+1C2+8n+1C3+⋯)The expression
82 can be further evaluated as
26. Thus, the binomial expansion shows that after simplification, the given expression is a multiple of
26.
Therefore, the maximum value of
p such that the expression is divisible by
2p is:
6