Domain Analysis: Finding Valid Inputs for y=-(x-2 6/19)²-2

Question

Find the positive and negative domains of the function below:

y=(x2619)22 y=-\left(x-2\frac{6}{19}\right)^2-2

Step-by-Step Solution

To solve this problem, we must analyze the quadratic function y=(x2619)22 y = -\left(x - 2\frac{6}{19}\right)^2 - 2 to determine its positive and negative domains.

  • Step 1: Identify the vertex and direction
    The given function is in the form y=a(xh)2+k y = a(x - h)^2 + k , where a=1 a = -1 , h=2619 h = 2\frac{6}{19} , and k=2 k = -2 . The vertex of the parabola is at (2619,2) (2\frac{6}{19}, -2) .
  • Step 2: Analyze the direction of the parabola
    Since a=1 a = -1 (negative), the parabola opens downward. This indicates the vertex is at the maximum point of the parabola.
  • Step 3: Determine the function's values
    Since the maximum value of the function (at the vertex) is y=2 y = -2 , and the parabola opens downward, the function cannot be positive anywhere. It is always less than or equal to 2-2, so it's negative for all x x .
  • Step 4: Establish the positive and negative domains
    Since the function is always negative, there are no positive domains. Therefore, the negative domain for the function is all real numbers x \>.

Therefore, the positive and negative domains are:

\( x > 0 : none

x<0: x < 0 : all x x

Answer

x > 0 : none

x < 0 : all x x