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

Barbados_Slim
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Homework Statement


Prove that
<br /> 11^n - 4^n<br />
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
<br /> 11(11^k)-4(4^k)<br />
but after this point I get stuck. Any help would be appreciated.
 
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Use that 11=7+4.
 

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