结合两个不同度数的多项式方程

我有两条多项式回归线

  1. v=lm(game_rating~poly(votes,2),data=board_games)
  2. t=lm(game_rating~poly(timeplay,4),data=board_games)

Now the question is how to combine these two lines into one to get a new regression game_rating=f(votes,timeplay). What can I do to add them together?

I tried to add them using "+" but r shows up in error that non-numeric argument to binary operator.

vt=lm(game_rating~poly(votes,2),data=board_games)+lm(game_rating~poly(timeplay,4),data=board_games)

*Notes: regression line 1 is between predictor games_rating and variable votes and polynomial with degree 2 is the best line that can make the prediction. Same for line 2.