FERMAT 2000 Problem 18

Past Contests FERMAT FERMAT - 2000
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1

If P=3^{2000}+3^{-2000} and Q=3^{2000}-3^{-2000} then the value of P^2-Q^2 is

Answer Choices
A. 3^{4000}
B. 2\times3^{-4000}
C. 0
D. 2\times3^{4000}
E. 4