# $$f(9-x)=f(9+x)$$

Algebra Level 2

Function $$f(x)=x^2+ax+b$$ satisfies $f(9-x)=f(9+x)$ for all real numbers $$x.$$ If the graph $$y=f(x)$$ passes through $$P=(0, 5),$$ what is the value of $$b-a?$$

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