Question

If f(x) is a polynomial function such that f(x) f(1/x) =f(x) + f(1/x) and f(3) = - 80 then f(x) - f(1/x) =
(A) 1/x^4- x^4
(B) -1/x^4+x^4
(C) x^4+1/x^4
(D) x^4-1/x^4
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Answer 1

Answer:

1+1+1+1+1+1-1+1+1+1+1+1++11+1+1+1+1+1+1+1+1+1+1+1++11++1-11-1-=2