9. $x=4$

11. $x={\displaystyle \frac{5}{3}}$

13. $x=\pm {\displaystyle \frac{7}{2}}$

15. $\varnothing$

17. $x=1$

19. $x={\displaystyle \frac{1}{2}}$

21. $x=\pm 9$

23. $x=10\text{,}000$

25. $x={\displaystyle \frac{\text{ln }3}{\text{ln }2}}\approx 1.585$

27. $x=\left({\displaystyle \frac{\text{ln }15-3\text{ ln }2}{2\text{ln }2}}\right)\approx 0.453$

29. $x=-1+\text{ln }3\approx 0.099$

31. $x={\displaystyle \frac{\text{ln }17-\text{ln }5}{\text{ln }2}}\approx 1.766$

33. $x={\displaystyle \frac{\text{ln }10-\text{ ln }3+\text{ln }4}{2\text{ln }4}}\approx 0.934$

35. $x=2+\text{ln }2\approx 2.693$

37. $x={\displaystyle \frac{\text{ln }5}{\text{ln }5+\text{ln }2}}\approx 0.699$

39. $x={\displaystyle \frac{\text{ln }2-6\text{ln }3}{4\text{ln }3+\text{ln }2}}\approx -1.159$

41. $x={\displaystyle \frac{\text{ln }2-\text{ln }3-\text{ln }5}{\text{ln }5-\text{ln }3}}\approx -3.944$

43. $t={\displaystyle \frac{\text{ln }2}{\text{ln}(1.065)}}\approx 11.007$

45. $x={\displaystyle \frac{\text{ln }7}{\text{ln }2}}\approx 2.807$

47. $x={\displaystyle \frac{\text{ln }2}{\text{ln }3}},{\displaystyle \frac{\text{ln }4}{\text{ln }3}}\approx 0.631,1.262$

49. $x={\displaystyle \frac{\text{ln }4}{\text{ln }3}}\approx 1.262$

51. $x=\text{ln }3\approx 1.099$

53. $x={\displaystyle \frac{\text{ln }5-\text{ln }3}{2\text{ln }3}}\approx 0.232$

55. $x={\displaystyle \frac{\text{ln }2}{\text{ln }3}}\approx 0.631$

57. $x={\displaystyle \frac{\text{ln }18-\text{ln }7}{\text{ln }3}}\approx 0.860$

59. $\varnothing$

61. $x=-{\displaystyle \frac{49}{20}}$

63. $x=3,-2$

65. $x=5,2$

67. $x=8$

69. $x=1$

71. $x=3$

73. $x=4$

75. $\varnothing$

77. $x={\displaystyle \frac{2}{3}},{\displaystyle \frac{5}{2}}$

79. $a=30,k=2;500$

81. $a=5,k={\displaystyle \frac{1}{2}};31$

83. $a=2,k=\text{ln }\left({\displaystyle \frac{17}{2}}\right);0.068$

85. $a=-2,k=\text{ln }\left({\displaystyle \frac{11}{18}}\right);-7.902$

87. $x\ge {\displaystyle \frac{\text{ln }2}{\text{ln }0.3}}$

89. $x\le 0$

91. $(-3,17)$

93. $x\ge e+5$

95. $\left({\displaystyle \frac{7}{3}},5\right)$

97. $x>{\displaystyle \frac{1}{2}}\text{ln }2$

99. $x\ge -\text{ln }2$