I have to choose the best way to model the relationship between years' experience and time taken to master a new skill. The curve seems to be quadratic, and a quadratic model does have a very high r^2 (over .90). However, as is common in polynomial regression, there is a high degree of multicollinearity. So I corrected for this using mean centering (taking from experience its mean; and then calculating experience^2 by squaring the new mean centered variable). This reduced multicollinearity.

However my problem is then how to describe the model. Normally I would write, the model is, as below, where y = time taken to master the skill (hours) and x = experience (years). However, how would one do this following mean-centering?

would you write, where x is experience in years mean-centered? and what about y?

many thanks