1. $$P(t) = 45000 + 1700t.$$
2. $$P(t) = 69000 + 2500t.$$
3. $$40 - 2n$$ dollars.
4. $$20 + 0.50n$$ dollars.
5. Rate of change: 10¢ per minute. Initial value: $24 each month, independently of calls made/received. 6. Rate of change: 4¢ per minute. Initial value:$26 each month, independently of calls made/received.
7. $$f(x) = 2 + \tfrac{3}{5}(x-5)$$ (or equivalent algebraic expression).
8. $$f(x) = 1 - \tfrac{1}{2}(x-5)$$ (or equivalent algebraic expression).
9. $$y = 4 + 3(x-2)$$ (or equivalent algebraic expression).
10. $$y = 5 + 2(x-1)$$ (or equivalent algebraic expression).
11. $$y = 4 - \tfrac{1}{3}(x+1)$$ (or equivalent algebraic expression).
12. $$y = 8 - \tfrac{1}{3}(x-8)$$ (or equivalent algebraic expression).
13. $$y = -3 - \tfrac{3}{2}x$$ (or equivalent algebraic expression).
14. $$y = 4 + \tfrac{4}{5}x$$ (or equivalent algebraic expression).
15. $$y = 1 + \tfrac{2}{3}x$$ (or equivalent algebraic expression).
16. $$y = 5 - \tfrac{5}{4}x$$ (or equivalent algebraic expression).
17. $$p = 34 - \tfrac{1}{250}n.$$
18. $$y = 45 - \tfrac{1}{2}n.$$
19. E
20. F
21. D
22. C
23. B
24. A
25. Use a calculator
26. Use a calculator
27. Use a calculator
28. Use a calculator
29. $$(-1, 1).$$
30. $$(-2, 1).$$
31. 111.11 miles
32. If you use no more than 2500 Kilobytes.
33. (a) $$R(t) = 16 - 2.1t.$$ (b) $$R(5) = 5.5$$ billion cubic feet of helium. (c) In 2017.
34. (d) $$R(t) = 1820 - 25t.$$ (e) $$R(7) = 1645$$ billion barrels. (f) In 72.8 years.