According to Remainder Theorem for the polynomials, for every polynomial P(x) there exist such polynomials G(x) and R(x), that
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When the polynomial in P(x) is divided by (x + a), then there exist such polynomials G(x) and R(x), that P(x)=(x+a)G(x)+R(x). Note that for x=-a:
P(-a)=(-a+a)G(-a)+R(-a)=0·G(a)+R(-a)=R(-a).
This means that P(-a) is the remainder, not P(a).
Answer: correct choice is B.