Given f(x)=ax2+bx+cf(x) = ax^2 + bx + cf(x)=ax2+bx+c, if f(x+1)−f(x)=8x+3f(x+1) - f(x) = 8x + 3f(x+1)−f(x)=8x+3, what is the value of aaa?
111
222
444
888