Vertex Form Explanation: The vertex form of a parabola is y=a(x−h)2+k, where (h,k) is the vertex.For y=−4(x−2)2−1, the vertex is (h,k)=(2,−1).
Axis of Symmetry: The axis of symmetry is the line that passes through the vertex and is parallel to the y-axis.So, the axis of symmetry is x=h, which is x=2.
Range Determination: The range of the function depends on the direction the parabola opens and the vertex.Since the coefficient of (x−2)2 is −4, the parabola opens downwards.
Downward-Opening Parabola: For a downward-opening parabola, the range is all y-values less than or equal to the y-coordinate of the vertex.So, the range is y≤−1.