Answer:
2x^2 + 6x + 2
Explanation:
5 + 3x - x^2 + (3x^2 - 5x + 4 + 8x - 7) =
= 5 + 3x - x^2 + 3x^2 + 3x - 3
= 2x^2 + 6x + 2
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