# Just for fun!-XI

Algebra Level 3

Let $$F(x)$$ be a unique polynomial of degree $$4$$ such as $$F(165)=20$$

$$F(42)=F(69)=F(96)=F(123)=13$$

Compute $$F(1)-F(2)+F(3)-F(4)+...+F(165)$$

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