Difference between revisions of "1990 AHSME Problems/Problem 30"
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Let <math>R_n=\frac{1}{2}(a^n+b^n)</math> for each non-negative integer <math>n</math> where <math>a=3+2\sqrt{2}</math> and <math>b=3-2\sqrt{2}</math>. The value of <math>R_{12345}</math> is an integer. What is its units digit? | Let <math>R_n=\frac{1}{2}(a^n+b^n)</math> for each non-negative integer <math>n</math> where <math>a=3+2\sqrt{2}</math> and <math>b=3-2\sqrt{2}</math>. The value of <math>R_{12345}</math> is an integer. What is its units digit? | ||
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Revision as of 12:51, 5 July 2013
Let 
for each non-negative integer 
where 
and 
. The value of 
is an integer. What is its units digit?
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