1. The problem asks if the function $B(t)$, representing temperature in Boston over time $t$ (hours after midnight), is one-to-one.
2. A function is one-to-one if each output corresponds to exactly one input. This means the function passes the Horizontal Line Test: no horizontal line intersects the graph more than once.
3. Since temperature can repeat at different times (e.g., morning and evening), $B(t)$ is generally not one-to-one unless specified otherwise.
4. For the graph of $y=f(x)$ on $-6 \leq x \leq 6$, to check if $f$ is one-to-one, apply the Horizontal Line Test: if any horizontal line crosses the graph more than once, $f$ is not one-to-one.
5. The graph has three segments: increasing, sharply rising, then descending. Because it descends after rising, some horizontal lines will intersect the graph twice.
6. Therefore, $f$ is not one-to-one on its domain.
7. Find the inverse of $y=\sqrt{x}+3$.
8. Start by writing $y=\sqrt{x}+3$.
9. Swap $x$ and $y$ to find the inverse: $x=\sqrt{y}+3$.
10. Solve for $y$:
$$x-3=\sqrt{y}$$
$$y=(x-3)^2$$
11. The domain of the original function is $x \geq 0$ (since square root is defined for non-negative $x$).
12. The range of the original function is $y \geq 3$ (since $\sqrt{x} \geq 0$).
13. For the inverse, domain and range swap:
- Domain of $f^{-1}$ is $x \geq 3$.
- Range of $f^{-1}$ is $y \geq 0$.
14. Let $f(x) = \frac{1}{x+5}$.
15. Find the inverse $f^{-1}$:
$$y=\frac{1}{x+5}$$
Swap $x$ and $y$:
$$x=\frac{1}{y+5}$$
Solve for $y$:
$$x(y+5)=1$$
$$xy+5x=1$$
$$xy=1-5x$$
$$y=\frac{1-5x}{x}$$
16. Domain of $f$ is all real numbers except $x=-5$ (denominator zero).
17. Range of $f$ is all real numbers except $0$ (since $\frac{1}{x+5}$ never equals zero).
18. Domain of $f^{-1}$ is range of $f$, so all real numbers except $0$.
19. Range of $f^{-1}$ is domain of $f$, all real numbers except $-5$.
20. It is possible to find domain and range of $f^{-1}$ without explicit formula by swapping domain and range of $f$.
21. For function $g$ with vertical asymptote at $x=-5$ and given values:
| x | g(x) |
|---|-------|
| -5 | undefined |
| -2 | -14 |
| 0 | -11 |
| 3 | -1 |
| 6 | 0 |
22. a. The y-intercept of $g^{-1}$ is the $y$-value when $x=0$ for $g^{-1}$, which corresponds to $x=0$ in $g$.
23. Since $g(0)=-11$, the point $(0,-11)$ is on $g$, so $( -11, 0)$ is on $g^{-1}$.
24. Therefore, the y-intercept of $g^{-1}$ is $-11$.
25. b. The horizontal asymptote of $g$ corresponds to the vertical asymptote of $g^{-1}$.
26. Since $g$ has vertical asymptote at $x=-5$, $g^{-1}$ has horizontal asymptote at $y=-5$.
Final answers:
- $B(t)$ is not one-to-one.
- $f$ is not one-to-one.
- Inverse of $y=\sqrt{x}+3$ is $y=(x-3)^2$ with domain $x \geq 3$ and range $y \geq 0$.
- Domain of $f^{-1}$ is all real numbers except $0$, range is all real numbers except $-5$.
- Y-intercept of $g^{-1}$ is $-11$.
- Horizontal asymptote of $g^{-1}$ is $y=-5$.
Inverse Functions E9A2C8
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