More on quadratic models o Suppose that the coefficient on x is positive and the coefficient on x2 is negative o Then y is increasing in x at first, but w eventually turn around and be decreasing in x For b>0 and B2<o the turning point will be at x= B/2B, Economics 20- Prof anderson 9Economics 20 - Prof. Anderson 9 More on Quadratic Models Suppose that the coefficient on x is positive and the coefficient on x 2 is negative Then y is increasing in x at first, but will eventually turn around and be decreasing in x ( ) 1 2 * 1 2 ˆ 2 ˆ will be at 0 the turning point ˆ 0 and ˆ For b b b b =   x