Solutions

Solutions to Try Its

1. (2,)

2. (5,)

3. The domain is (0,), the range is (,), and the vertical asymptote is = 0.
Graph of f(x)=log_(1/5)(x) with labeled points at (1/5, 1) and (1, 0). The y-axis is the asymptote.

4. The domain is (4,), the range (,), and the asymptote = –4.
Graph of two functions. The parent function is y=log_3(x), with an asymptote at x=0 and labeled points at (1, 0), and (3, 1).The translation function f(x)=log_3(x+4) has an asymptote at x=-4 and labeled points at (-3, 0) and (-1, 1).

5. The domain is (0,), the range is (,), and the vertical asymptote is = 0.
Graph of two functions. The parent function is y=log_2(x), with an asymptote at x=0 and labeled points at (1, 0), and (2, 1).The translation function f(x)=log_2(x)+2 has an asymptote at x=0 and labeled points at (0.25, 0) and (0.5, 1).

6. The domain is (0,), the range is (,), and the vertical asymptote is = 0.
Graph of two functions. The parent function is y=log_4(x), with an asymptote at x=0 and labeled points at (1, 0), and (4, 1).The translation function f(x)=(1/2)log_4(x) has an asymptote at x=0 and labeled points at (1, 0) and (16, 1).

7. The domain is (2,), the range is (,), and the vertical asymptote is = 2.

Graph of f(x)=3log(x-2)+1 with an asymptote at x=2.

8. The domain is (,0), the range is (,), and the vertical asymptote is = 0.
Graph of f(x)=-log(-x) with an asymptote at x=0.

9. x3.049

10. = 1

11. f(x)=2ln(x+3)1

Solutions to Odd-Numbered Exercises

1. Since the functions are inverses, their graphs are mirror images about the line = x. So for every point (a,b) on the graph of a logarithmic function, there is a corresponding point (b,a) on the graph of its inverse exponential function.

3. Shifting the function right or left and reflecting the function about the y-axis will affect its domain.

5. No. A horizontal asymptote would suggest a limit on the range, and the range of any logarithmic function in general form is all real numbers.

7. Domain: (,12); Range: (,)

9. Domain: (174,); Range: (,)

11. Domain: (5,); Vertical asymptote: = 5

13. Domain: (13,); Vertical asymptote: x=13

15. Domain: (3,); Vertical asymptote: = –3

17. Domain: (37,); Vertical asymptote: x=37 ; End behavior: as x(37)+,f(x) and as x,f(x)

19. Domain: (3,) ; Vertical asymptote: = –3; End behavior: as x3+f(x) and as xf(x)

21. Domain: (1,); Range: (,); Vertical asymptote: = 1; x-intercept: (54,0); y-intercept: DNE

23. Domain: (,0); Range: (,); Vertical asymptote: = 0; x-intercept: (e2,0); y-intercept: DNE

25. Domain: (0,); Range: (,); Vertical asymptote: = 0; x-intercept: (e3,0); y-intercept: DNE

27. B

29. C

31. B

33. C

35.
Graph of two functions, g(x) = log_(1/2)(x) in orange and f(x)=log(x) in blue.

37.
Graph of two functions, g(x) = ln(1/2)(x) in orange and f(x)=e^(x) in blue.

39. C

41.
Graph of f(x)=log_2(x+2).

43.
Graph of f(x)=ln(-x).

45.
Graph of g(x)=log(6-3x)+1.

47. f(x)=log2((x1))

49. f(x)=3log4(x+2)

51. = 2

53. x2.303

55. x0.472

57. The graphs of f(x)=log12(x) and g(x)=log2(x) appear to be the same; Conjecture: for any positive base b1, logb(x)=log1b(x).

59. Recall that the argument of a logarithmic function must be positive, so we determine where x+2x4>0 . From the graph of the function f(x)=x+2x4, note that the graph lies above the x-axis on the interval (,2) and again to the right of the vertical asymptote, that is (4,). Therefore, the domain is (,2)(4,).