I need to Prove that 6^(2n) -1 is divisible by 35. Using mathematical induction.

Hint given : use the equality 6^2n = 36^n = ( 35+1)^n

So step one is to verify if this works for 1, and so I did 6^(2*1) - 1 = 36-1=35 so it works.

In step two I need to assume that this is true for an arbitrary n,

Finally in the deductive proof I need to show that this holds for n+1.

So I set it up as follows (35+1)^(n+1) - 1 = 35k, where k is some constant.

I don't know where to go from here.