Ankit enrolled in the EDM course but had to miss a few classes due to mandatory election duty during India$$s General Election. During his absence$,$ the class was given an assignment to analyze the relationship between automobile sales $($y$)$ and their prices $($X$).$ Ankit estimated the following two models to explore this relationship:

yi $=\backslash$beta $1+\backslash$beta $2$X $+$ ui $(1)$

logyi $=\backslash$alpha $1+\backslash$alpha $2$ log X $+$ ui $(2)$

a$.$ Ankit is unsure how to interpret the coefficients $\backslash$beta $2$ and $\backslash$alpha $2$ in these models. Can you help Ankit interpret $\backslash$beta $2$ and $\backslash$alpha $2$ in these models?

b$.$ After reviewing the models, you notice that an important variable, Income $($X$2),$ which could affect automobile sales, is missing. Explain to Ankit the implications of not including a crucial$/$essential variable in the model.