Hi everyone I need a little help, Im stuck.
I have to prove by induction that:
is exactly divisible by 7 for all positive integers of n.
Now what I have done is:
1)
If
is divisible by 7
=>(
)-----> Pn statement
where a is a positive integer
2)
statement where n=1
=>
LHS:
RHS:
Therefore
is true.
3) Assuming
to be true where n=k
=>
4) Therefore
Now here is where Im stuck, Im not getting to factor out a 7 i.e.
getting 7(some integer) to prove that
is divisible by 7.
Any help would be greately appreciated.