sat-dog

Choice A is correct. The graph of a quadratic equation in the form =( -)2 + y a x h k, where a, h, and k are positive constants, is a parabola that ( ) ( )= 1( - )2+ opens upward with vertex h, k. The given functiofn x x 7 3 is in the 9 =( -)2 + = ( ) =1 = = form y a x h k, where y f x , a , h 7, and k 3. Therefore, the = ( ) 9 ( ) graph of y f x is a parabola that opens upward with vertex 7, 3 . Since the parabola opens upward, the vertex is the lowest point on the graph. It follows that = ( ) the y-coordinate of the vertex of the graph of y f x is the minimum value of ( ) ( ) ( )= 1( - )2+ f x . Therefore, the minimum value of f x is 3. It’s given thaft x x 7 3 9 represents the metal ball’s height above the ground, in inches, x seconds after it started moving on a track. Therefore, the best interpretation of the vertex of the = ( ) graph of y f x is that the metal ball’s minimum height was 3 inches above the ground. Choice B is incorrect and may result from conceptual or calculation errors. Choice C is incorrect and may result from conceptual or calculation errors. Choice D is incorrect and may result from conceptual or calculation errors.