price~rooms:  STC=42825531146,45  SEC=20732259424,69  SRC=22093271721,76   R2(a mano)=0,4841
price~nox  :  STC=42825531146,45  SEC=7773157316,47  SRC=35052373829,98   R2(a mano)=0,1815

Comparacion con rho^2 (recuerde: en regresion simple R2 = rho_xy^2):
corr(price,rooms)^2 = 0,4841
corr(price,nox)^2   = 0,1815