# Polynomial

Algebra Level 5

The roots of the polynomial $$P (x) = x^{4} - x^{3} - x^{2}-1$$ are $$a, b, c,$$ and $$d.$$ If $$f(x) = x^{6} - x^{5} - x^{3} - x^{2} - x,$$ what is the value of $$f(a) + f(b) + f(c) + f(d)?$$

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