1. **State the problem:** We are given the function $f(x) = 4x^4 - 8$ and want to understand its properties.
2. **Formula and rules:** This is a quartic polynomial function of the form $f(x) = ax^4 + bx^3 + cx^2 + dx + e$. Here, $a=4$, $b=0$, $c=0$, $d=0$, and $e=-8$.
3. **Find intercepts:**
- **y-intercept:** Set $x=0$, then $f(0) = 4(0)^4 - 8 = -8$.
- **x-intercepts:** Set $f(x)=0$:
$$4x^4 - 8 = 0$$
$$4x^4 = 8$$
$$\cancel{4}x^4 = \cancel{4}2$$
$$x^4 = 2$$
$$x = \pm \sqrt[4]{2}$$
4. **Find extrema:**
- Take the derivative:
$$f'(x) = 16x^3$$
- Set $f'(x) = 0$:
$$16x^3 = 0$$
$$x = 0$$
- Second derivative test:
$$f''(x) = 48x^2$$
$$f''(0) = 0$$ (inconclusive, but since $f(x)$ is a quartic with positive leading coefficient, $x=0$ is a minimum).
5. **Summary:**
- The graph has a minimum at $(0, -8)$.
- It crosses the y-axis at $(0, -8)$.
- It crosses the x-axis at $x = \pm \sqrt[4]{2}$.
- The function grows large positively as $x \to \pm \infty$.
**Final answer:** The function $f(x) = 4x^4 - 8$ has x-intercepts at $x = \pm \sqrt[4]{2}$ and a minimum point at $(0, -8)$.
Quartic Function A3137C
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