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Algebra Difficulty 4.8 AIME Find the answer

Let Q(x)=x2+2x+3Q(x)=x^{2}+2x+3, and suppose that P(x)P(x) is a polynomial such that P(Q(x))=x6+6x5+18x4+32x3+35x2+22x+8P(Q(x))=x^{6}+6x^{5}+18x^{4}+32x^{3}+35x^{2}+22x+8. Compute P(2)P(2).

A number or a short expression. Spacing and $ signs are ignored.

Solution

Note that Q(1)=2Q(-1)=2. Therefore, P(2)=P(Q(1))=16+1832+3522+8=2P(2)=P(Q(-1))=1-6+18-32+35-22+8=2.

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