A = Point(xAxis)
B = Point(xAxis)
C = Point(xAxis)
D = Point(yAxis)
f(x) = (x - x(A)) * (x - x(B)) * (x - x(C)) * (-1.0 * y(D)) / (x(A) * x(B) * x(C))
Text1: "f(x) = " + (Simplify[f(x)])