Solve the Quadratic Inequality: Finding X When -x²-4 > 0

Question

Given the function:

y=x24 y=-x^2-4

Determine for which values of x the following holds:

f\left(x\right) > 0

Step-by-Step Solution

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

  • Step 1: Identify the form and behavior of the given quadratic function.
  • Step 2: Analyze the vertical position of the function's vertex.
  • Step 3: Determine inequality feasibility for positive y y .

Step 1: The function given is y=x24 y = -x^2 - 4 , which is a parabola opening downwards because of the negative coefficient of x2 x^2 .

Step 2: The vertex of this parabola occurs at x=b2a=0 x = -\frac{b}{2a} = 0 , considering no x x term present (i.e., b=0 b = 0 ). The vertex value of y y is f(0)=024=4 f(0) = -0^2 - 4 = -4 .

Step 3: The vertex, being the highest point at (0,4)(0, -4), means the entire parabola remains below the x-axis.

Since the maximum point is negative and the parabola only descends from this vertex, the function y=x24 y = -x^2 - 4 remains less than zero for every x x . There are no x x values making y y positive.

Therefore, the solution is No x.

Answer

No x