1. **State the problem:** We are given a parabola centered at the origin with vertex at $(0,5)$, opening downward, and x-intercepts approximately at $(-2.6,0)$ and $(2.6,0)$. We need to find:
a. The domain of the function.
b. The range of the function.
c. The x-intercepts.
d. The y-intercept.
e. The missing function values $f(-2)$ and $f(2)$.
2. **Formula and properties:** The parabola is symmetric about the y-axis and opens downward, so its equation can be written as:
$$f(x) = a x^2 + k$$
where $a < 0$ (since it opens downward) and $k$ is the vertex's y-coordinate.
Given vertex $(0,5)$, the equation is:
$$f(x) = a x^2 + 5$$
3. **Find $a$ using x-intercepts:** The parabola crosses the x-axis at approximately $x = \pm 2.6$, so:
$$0 = a (2.6)^2 + 5$$
$$a (2.6)^2 = -5$$
$$a = \frac{-5}{(2.6)^2} = \frac{-5}{6.76} \approx -0.74$$
4. **Write the function:**
$$f(x) = -0.74 x^2 + 5$$
5. **Domain:** The domain of any parabola is all real numbers:
$$\text{Domain} = (-\infty, \infty)$$
6. **Range:** Since the parabola opens downward with vertex at $5$, the maximum value is $5$ and it goes down to negative infinity:
$$\text{Range} = (-\infty, 5]$$
7. **x-intercepts:** Given as approximately $(-2.6, 0)$ and $(2.6, 0)$.
8. **y-intercept:** At $x=0$,
$$f(0) = -0.74 \times 0^2 + 5 = 5$$
So the y-intercept is $(0,5)$.
9. **Find missing values:**
$$f(-2) = -0.74 \times (-2)^2 + 5 = -0.74 \times 4 + 5 = -2.96 + 5 = 2.04$$
$$f(2) = -0.74 \times 2^2 + 5 = -0.74 \times 4 + 5 = 2.04$$
**Final answers:**
- Domain: $(-\infty, \infty)$
- Range: $(-\infty, 5]$
- x-intercepts: $(-2.6, 0)$ and $(2.6, 0)$
- y-intercept: $(0,5)$
- $f(-2) = 2.04$
- $f(2) = 2.04$
Parabola Domain Range 06Bfe7
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