Answer:
Step-by-step explanation:
To prove that is a multiple of 7.
Proof by induction:
Let n =1. Then we have 8-1 =7 is a multiple of 7
Thus the P(1) is true.
Let us assume that P(n) is true.
= 7l is true for some integer l
To check for P(n+1)
=LHS
=
Thus we find that this is also a multiple of 7.
If true for n, then true for n+1
Hence we find that since true for 1, we have it is true for all natural numbers.