Parabola Domain Analysis: Finding x-Values Where f(x) > 0

Question

The graph of the function below does not intersect the x x -axis.

The parabola's vertex is marked A.

Find all values of x x where
f\left(x\right) > 0 .

AAAX

Step-by-Step Solution

To solve this problem, let's analyze the key characteristics of the parabola:

  • Since the parabola does not intersect the x x -axis, it indicates that it is entirely either above or below the x x -axis.
  • The graph of a parabola ax2+bx+c ax^2 + bx + c does not intersect the x x -axis when its discriminant b24ac b^2 - 4ac is negative. Thus, it does not have any real roots.
  • If the parabola opens upwards, then the function is entirely above the x x -axis if a>0 a > 0 and below if a<0 a < 0 .
  • Given the problem indicates the parabola never reaches or crosses the x x -axis and the absence of real roots, a positive opening parabola cannot reach positive territory in when not intersecting the x-axis.

Since the parabola's graph neither touches nor crosses the x x -axis and isn't stated to be always positive or negative, we conclude:

The function does not have a positive domain.

Answer

The function does not have a positive domain.