Question No. 48
a linear model has the following characteristics:

a dependent variable (y)
one continuous variable (x1), including a quadratic term (x12)
one categorical (d with 3 levels) predictor variable and an interaction term (d by x1)

how many paramters, including the intercept, are associated with this model?

答案是7，请教一下大家是怎么的出来的。谢谢哈