sat suite question viewer
When the quadratic function is graphed in the xy-plane, where , its vertex is . One of the x-intercepts of this graph is . What is the other x-intercept of the graph?
Explanation
Choice B is correct. Since the line of symmetry for the graph of a quadratic function contains the vertex of the graph, the x-coordinate of the vertex of the graph of is the x-coordinate of the midpoint of its two x-intercepts. The midpoint of two points with x-coordinates and has x-coordinate , where . It′s given that the vertex is and one of the x-intercepts is . Substituting for and for in the equation yields . Multiplying each side of this equation by yields . Adding to each side of this equation yields . Therefore, the other x-intercept is .
Choice A 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.