How do you deal with the dark (negative) side of functions?

Let $$f(x)$$ be a quartic polynomial in the form $$ax^4+bx^3+cx^2+dx+e$$ where

$f(-7) = 4636 , f(-6) = 2504 , f(-5) = 1212.$

Given that $$a, b,c , d$$ and $$e$$ are all positive integers less than 5. Evaluate the addition of the two 3-digit integers, $$\overline{abc}+\overline{cde}$$.

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