Function Evaluation 73781B
1. Problem: Given functions and piecewise definitions, find expressions and values for g(x), f(g(11)), and solve functional equations.
2. For the first problem, f(x) = 3x + 1 and g(x) is defined piecewise as:
$$g(x) = \begin{cases} 3x + 10, & x < 3 \\ 3x - 8, & x \geq 3 \end{cases}$$
We want to find which expression g(x) equals among options involving absolute values.
3. Consider the function f(x) = 3x + 1. To express g(x) in terms of absolute values, check the behavior at x=3:
- For x < 3, g(x) = 3x + 10
- For x \geq 3, g(x) = 3x - 8
4. Test option D) $|x - 3|$ scaled by 3:
$$3|x - 3| = \begin{cases} 3(3 - x) = 9 - 3x, & x < 3 \\ 3(x - 3) = 3x - 9, & x \geq 3 \end{cases}$$
This does not match g(x).
5. Test option A) $3|x - 1|$:
$$3|x - 1| = \begin{cases} 3(1 - x) = 3 - 3x, & x < 1 \\ 3(x - 1) = 3x - 3, & x \geq 1 \end{cases}$$
Does not match g(x).
6. Test option B) $|x| - 3$:
$$|x| - 3$$ is continuous but does not match the piecewise linear form of g(x).
7. Test option C) $3|x| - 1$:
$$3|x| - 1$$ is symmetric about zero, not matching g(x).
8. None of the options exactly match g(x) as given, so g(x) is as defined piecewise.
9. Next, given f(x) = 2x - 3, find g(x). The problem is incomplete for g(x) here; assuming g(x) is the same piecewise function or needs definition.
10. Calculate f(g(11)):
Since 11 \geq 3, use $g(11) = 3(11) - 8 = 33 - 8 = 25$.
Then,
$$f(g(11)) = f(25) = 2(25) - 3 = 50 - 3 = 47$$
11. For the rational expressions:
Given
$$\frac{2x + 5}{3} = 2x^2 + 5x - 2$$
and
$$\frac{2x + 5}{3} = 4x^2 - 6x + 3$$
These are inconsistent equalities; likely a misunderstanding or separate equations.
12. For function
$$f(x) = \frac{x}{x} + x^2 - x$$
Simplify:
$$\frac{x}{x} = 1 \quad (x \neq 0)$$
So,
$$f(x) = 1 + x^2 - x$$
13. For
$$f(x) = 4^{3x^{-2}}$$
and
$$g(x) = \log_2(x + 1)$$
Calculate
$$f(g(3))$$
First,
$$g(3) = \log_2(3 + 1) = \log_2(4) = 2$$
Then,
$$f(g(3)) = 4^{3 \cdot 2^{-2}} = 4^{3 \cdot \frac{1}{4}} = 4^{\frac{3}{4}}$$
Since
$$4 = 2^2,$$
we have
$$4^{\frac{3}{4}} = (2^2)^{\frac{3}{4}} = 2^{2 \cdot \frac{3}{4}} = 2^{\frac{3}{2}} = 2^{1.5} = 2 \sqrt{2}$$
14. For the recurrence relation:
$$f(x + 1) = 3f(x) - f(x - 1) + 2x$$
with initial values
$$f(1) = 6, \quad f(2) = 5$$
Find $f(5)$.
Calculate stepwise:
- $f(3) = 3f(2) - f(1) + 2 \cdot 2 = 3 \cdot 5 - 6 + 4 = 15 - 6 + 4 = 13$
- $f(4) = 3f(3) - f(2) + 2 \cdot 3 = 3 \cdot 13 - 5 + 6 = 39 - 5 + 6 = 40$
- $f(5) = 3f(4) - f(3) + 2 \cdot 4 = 3 \cdot 40 - 13 + 8 = 120 - 13 + 8 = 115$
Answer: $f(5) = 115$
15. Summary answers:
- $g(x)$ is the given piecewise function.
- $f(g(11)) = 47$
- Simplified $f(x) = 1 + x^2 - x$
- $f(g(3)) = 2 \sqrt{2}$
- $f(5) = 115$