1. Identify whether the following functions are polynomial or not, and if polynomial, find degree, leading coefficient, and constant term.
**a.** $$f(x) = 5x^2 - \frac{2}{3}x^3 - \frac{1}{3}x - \frac{4x^4 + 9x^3 - 2x + 9}{3}$$
Step 1: Simplify the expression inside the fraction:
$$\frac{4x^4 + 9x^3 - 2x + 9}{3} = \frac{4x^4}{3} + 3x^3 - \frac{2x}{3} + 3$$
Step 2: Rewrite entire function:
$$f(x) = 5x^2 - \frac{2}{3}x^3 - \frac{1}{3}x - \left(\frac{4x^4}{3} + 3x^3 - \frac{2x}{3} + 3\right)$$
Step 3: Distribute the minus sign:
$$f(x) = 5x^2 - \frac{2}{3}x^3 - \frac{1}{3}x - \frac{4x^4}{3} - 3x^3 + \frac{2x}{3} - 3$$
Step 4: Combine like terms:
- For $x^4$: $-\frac{4}{3}x^4$
- For $x^3$: $-\frac{2}{3}x^3 - 3x^3 = -\frac{2}{3}x^3 - \frac{9}{3}x^3 = -\frac{11}{3}x^3$
- For $x$: $-\frac{1}{3}x + \frac{2}{3}x = \frac{1}{3}x$
- For constant: $-3$
Step 5: Final simplified polynomial:
$$f(x) = -\frac{4}{3}x^4 - \frac{11}{3}x^3 + 5x^2 + \frac{1}{3}x - 3$$
- Degree: 4
- Leading coefficient: $-\frac{4}{3}$
- Constant term: $-3$
**b.** $$f(x) = 2\left(\frac{1}{3}\right) + \frac{3}{2} - \frac{1}{6}$$
Step 1: Calculate constants:
$$2 \times \frac{1}{3} = \frac{2}{3}$$
Step 2: Sum all constants:
$$\frac{2}{3} + \frac{3}{2} - \frac{1}{6} = \frac{4}{6} + \frac{9}{6} - \frac{1}{6} = \frac{12}{6} = 2$$
This is a constant function, which is a polynomial of degree 0.
- Degree: 0
- Leading coefficient: 2
- Constant term: 2
**c.** $$f(x) = 3(x^2)^3 - 4(x^2)^2 + 2(x+1)^2 + 5$$
Step 1: Simplify powers:
$$(x^2)^3 = x^{6}, \quad (x^2)^2 = x^{4}$$
Step 2: Expand $(x+1)^2 = x^2 + 2x + 1$
Step 3: Substitute:
$$f(x) = 3x^6 - 4x^4 + 2(x^2 + 2x + 1) + 5 = 3x^6 - 4x^4 + 2x^2 + 4x + 2 + 5$$
Step 4: Combine constants:
$$f(x) = 3x^6 - 4x^4 + 2x^2 + 4x + 7$$
- Degree: 6
- Leading coefficient: 3
- Constant term: 7
**d.** $$f(x) = -2(\sqrt{x})^3 + 5\sqrt{x} - 10$$
Step 1: Rewrite powers:
$$(\sqrt{x})^3 = (x^{1/2})^3 = x^{3/2}$$
Step 2: Expression becomes:
$$f(x) = -2x^{3/2} + 5x^{1/2} - 10$$
Since exponents are not whole numbers, this is not a polynomial.
**e.** $$f(x) = 3\pi^2 + 4$$
This is a constant function (number), so polynomial degree 0.
- Degree: 0
- Leading coefficient: $3\pi^2 + 4$
- Constant term: $3\pi^2 + 4$
Summary for question 1:
- a: Polynomial, degree 4, leading coefficient $-\frac{4}{3}$, constant $-3$
- b: Polynomial, degree 0, leading coefficient 2, constant 2
- c: Polynomial, degree 6, leading coefficient 3, constant 7
- d: Not polynomial
- e: Polynomial, degree 0, leading coefficient $3\pi^2 + 4$, constant $3\pi^2 + 4$
Polynomial Identification 5048B5
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