Parabola Properties: Analyzing Negative Values with Downward-Facing Curves and Vertex Position

Question

If a parabola is bending downwards and its vertex is above the x-axis, then it is always negative.

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Understand the form of the parabola.
  • Step 2: Analyze the nature of values above and below the x-axis.
  • Step 3: Determine if the parabola can have positive values.

Now, let's work through each step:

Step 1: Given the parabola is opening downwards, the quadratic formula can be defined as:
y=a(xh)2+k y = a(x-h)^2 + k , with a<0 a < 0 and k>0 k > 0 .

Step 2: Because the vertex is above the x-axis (k>0 k > 0 ), the vertex itself is positive when considered as a point (h,k h, k ).

Step 3: A parabola that opens downward will eventually intersect the x-axis, creating two roots unless it remains above the x-axis—which is not generally the case when k k is small enough. Therefore, for values of x x surrounding the vertex and large enough in magnitude, y y can be negative.

Conclusion: The parabola is not always negative as it can be positive near its vertex.

The statement in the problem is thus Incorrect.

Answer

Incorrect