Consider the Model Described by the Equation $$E ( y ) = \beta _ { 0 } + \beta _ { 1 } x + \beta _ { 2 } x ^ { 2 } + \beta _ { 3 } x ^ { 3 }$$

Multiple Choice

Consider the model described by the equation $$E ( y ) = \beta _ { 0 } + \beta _ { 1 } x + \beta _ { 2 } x ^ { 2 } + \beta _ { 3 } x ^ { 3 }$$ .Which term provides a nonlinear component to the model enabling the line to reverse the direction of curvature?

A) $\beta _ { 0 }$
B) $\beta _ { 1 } x$
C) $\beta _ { 2 } x ^ { 2 }$
D) $\beta _ { 3 } x ^ { 3 }$