When the graph has a low point, it has a minimum. 'a' is positive in that case. The coordinates of that low point are (1, -4). That point is the vertex.
The graph crosses the y-axis at y = -3, so the y-intercept is (0, -3).
The graph crosses the x-axis at (-1, 0) and (3, 0). These points represent the solution to the equation y = 0.
