Identify a, b, and c in the given quadratic function. What does the value of a tell you about the function?
Maximum Value: - 12 Domain: {all real numbers} Range: {f(x)|f(x)≤ - 12}
Practice makes perfect
Let's begin by rewriting our function in the general expression of a quadratic function, y=ax^2+bx+c.
f(x) = - x^2 -12 ⇔ f(x) = (- 1)x^2 + x + (- 12)
We can see that a = - 1, b = , and c = - 12.
Determining Maximum or Minimum Value
Before we determine the maximum or minimum recall that, if a>0, the parabola has a minimum value. Conversely, if a<0, the parabola has a maximum value.
In the given function, we have a=- 1, which is less than 0. Thus, the parabola will have a maximum value.
Finding the Maximum or Minimum Value
The minimum or maximum value of a parabola is always the y-coordinate of the vertex. We can find it by first looking for the x-coordinate of the vertex, - b2a.
Unless there is a specific restriction given in the context of the problem, the domain of a quadratic function is all real numbers. In this case, there is no restriction on the value of x. Since the maximum value of the function is - 12, the range is all real numbers less than or equal to - 12.
Domain:& {all real numbers}
Range:& {f(x)|f(x)≤ - 12}
