1. **State the problem:** We are given two functions $f(x) = 2x^2 + 1$ and $g(x) = 2x - 6$. We need to determine which of the statements A through E about $f$ and $g$ are true.
2. **Recall definitions and formulas:**
- The product of two functions $(f \cdot g)(x) = f(x) \times g(x)$.
- The difference of two functions $(f - g)(x) = f(x) - g(x)$.
- The sum of two functions $(f + g)(x) = f(x) + g(x)$.
- The domain of $f + g$ is the intersection of the domains of $f$ and $g$.
- The range depends on the function's outputs.
3. **Evaluate each statement:**
**A. $f \cdot g$ is a quadratic function.**
Calculate $f \cdot g$:
$$
(f \cdot g)(x) = (2x^2 + 1)(2x - 6) = 2x^2 \times 2x - 2x^2 \times 6 + 1 \times 2x - 1 \times 6 = 4x^3 - 12x^2 + 2x - 6
$$
This is a cubic function (degree 3), not quadratic (degree 2). So, statement A is **false**.
**B. $(f - g)(-2) = 19$**
Calculate $(f - g)(-2)$:
$$
(f - g)(-2) = f(-2) - g(-2)
$$
Calculate $f(-2)$:
$$
2(-2)^2 + 1 = 2 \times 4 + 1 = 8 + 1 = 9
$$
Calculate $g(-2)$:
$$
2(-2) - 6 = -4 - 6 = -10
$$
So,
$$
(f - g)(-2) = 9 - (-10) = 9 + 10 = 19
$$
Statement B is **true**.
**C. The range of $f + g$ is $y \geq 5.5$.**
Calculate $f + g$:
$$
(f + g)(x) = (2x^2 + 1) + (2x - 6) = 2x^2 + 2x - 5
$$
This is a quadratic function with leading coefficient positive ($2$), so it opens upward.
Vertex $x$-coordinate:
$$
x = -\frac{b}{2a} = -\frac{2}{2 \times 2} = -\frac{2}{4} = -0.5
$$
Calculate vertex $y$-value:
$$
(f + g)(-0.5) = 2(-0.5)^2 + 2(-0.5) - 5 = 2(0.25) - 1 - 5 = 0.5 - 1 - 5 = -5.5
$$
So the minimum value of $f + g$ is $-5.5$, not $5.5$. Statement C is **false**.
**D. The domain of $f + g$ is all real numbers.**
Both $f$ and $g$ are polynomials, which have domain all real numbers.
Therefore, the domain of $f + g$ is all real numbers. Statement D is **true**.
**E. The domain and range of $f \cdot g$ are all real numbers.**
We found $f \cdot g$ is cubic: $4x^3 - 12x^2 + 2x - 6$.
- Domain of a polynomial is all real numbers.
- Range of a cubic polynomial is all real numbers (since cubic functions go to $\pm \infty$).
So statement E is **true**.
**Final answers:**
- A: False
- B: True
- C: False
- D: True
- E: True
**Summary:** Statements B, D, and E are true.
Function Properties A2293B
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