Is 11^n - 4^n a Multiple of 7? Proving with Mathematical Induction

[Barbados_Slim]

Homework Statement

Prove that
$$11^n - 4^n$$
is a multiple of 7

Homework Equations

N/A

The Attempt at a Solution

I substituted k+1 in for n and simplified to get
$$11(11^k)-4(4^k)$$
but after this point I get stuck. Any help would be appreciated.

 

[Dick]

Use that 11=7+4.