- Thread starter
- #1

#### veronica1999

##### Member

- Jun 4, 2012

- 63

If Rn = 1/2(a^n + b^n) where a= 3+ 2root2 b= 3 - 2root2 and n= 0,1,2,3,4,5,...

then R12345 is an integer. Its units digit is..

I didn't have any ideas so I started to plug in numbers looking for a pattern.

I am sure this is not the right approach.

R0 = 1

R1 = 3

R2= 7

R3= 9

Could I get some help?

then R12345 is an integer. Its units digit is..

I didn't have any ideas so I started to plug in numbers looking for a pattern.

I am sure this is not the right approach.

R0 = 1

R1 = 3

R2= 7

R3= 9

Could I get some help?

Last edited: