Question: Decide whether the function is a polynomial function. If so, write it in standard form and state its leading term, leading coefficient, and degree. If not a polynomial function, state why.
(a) $v_0 t - \frac{1}{2} t^2$
(b) $f(x) = \frac{5}{3} x^2 - \sqrt{7} x^2 + 8 x^3 - \frac{1}{2} + \ldots$
1. **Problem Statement:**
Determine if each given function is a polynomial function. If yes, write it in standard form, and identify the leading term, leading coefficient, and degree.
2. **Recall:**
A polynomial function is a function of the form $$a_n x^n + a_{n-1} x^{n-1} + \cdots + a_1 x + a_0$$ where $n$ is a non-negative integer and all coefficients $a_i$ are real numbers.
3. **Part (a):** $v_0 t - \frac{1}{2} t^2$
- This is a sum of terms with variables raised to whole number powers: $t^1$ and $t^2$.
- The function can be written as $$-\frac{1}{2} t^2 + v_0 t$$ in standard form (descending powers).
- Leading term: $-\frac{1}{2} t^2$
- Leading coefficient: $-\frac{1}{2}$
- Degree: $2$
- Conclusion: This is a polynomial function.
4. **Part (b):** $f(x) = \frac{5}{3} x^2 - \sqrt{7} x^2 + 8 x^3 - \frac{1}{2} + \ldots$
- The terms shown are $8 x^3$, $\frac{5}{3} x^2$, $-\sqrt{7} x^2$, and $-\frac{1}{2}$.
- Combine like terms for $x^2$:
$$\frac{5}{3} x^2 - \sqrt{7} x^2 = \left(\frac{5}{3} - \sqrt{7}\right) x^2$$
- The function in standard form (descending powers) is:
$$f(x) = 8 x^3 + \left(\frac{5}{3} - \sqrt{7}\right) x^2 - \frac{1}{2} + \ldots$$
- Since the ellipsis ($\ldots$) is incomplete, we cannot confirm if the function contains only polynomial terms.
- If the omitted terms are polynomial terms (powers of $x$ with non-negative integers), then $f(x)$ is a polynomial.
- Leading term: $8 x^3$
- Leading coefficient: $8$
- Degree: $3$
5. **Summary:**
- (a) is a polynomial function of degree 2 with leading term $-\frac{1}{2} t^2$ and leading coefficient $-\frac{1}{2}$.
- (b) is a polynomial function of degree 3 with leading term $8 x^3$ and leading coefficient $8$ if the omitted terms are polynomial terms; otherwise, more information is needed.