The following estimated regression equation was developed for a model involving two independent variables.
ŷ = 40.7 + 8.63x₁ + 2.71x₂
After x₂ was dropped from the model, the least-squares method was used to obtain an estimated regression equation involving only x₁ as an independent variable.
ŷ = 42.0 + 9.01x₁
Give an interpretation of the coefficient of x₁ in both models.