9. ${\displaystyle \frac{4}{3}},\text{ rising}$

11. 0, horizontal

13. $-2.2,$ falling

15. 4, rising

17. ${\ell }_3$

19. ${\ell }_4$

21. 1

23. 2

25. $y=3x+5$

27. $y={\displaystyle \frac{1}{2}}x+4$

29. $y=-{\displaystyle \frac{3}{2}}x+4$

31. $y=-4$

33. $y=-x+1$

35. $y=3$

37. $y={\displaystyle \frac{2}{3}}x+{\displaystyle \frac{1}{3}}$

39. $y=-{\displaystyle \frac{7}{2}}x+2$

41. $x=5$

43. $y=0$

45. $y=14$

47. $y=-{\displaystyle \frac{2}{3}}x-4$

49. $y={\displaystyle \frac{4}{3}}x+4$

51. $y=7$

53. $y=-5$

55. $m=3$ x intercept: $2/3,$ y intercept $-2$

57. $m=-{\displaystyle \frac{1}{2}};$ y-intercept $=2;$x-intercept $=4$

59. $m={\displaystyle \frac{3}{2}};$ y-intercept $=3;$x-intercept $=-2$

61. m is undefined; no y-intercept; x-intercept $=5$

63. m is undefined; y-intercept $=$y-axis; x-intercept $=0$

67. ${\displaystyle \frac{x}{3}}+{\displaystyle \frac{y}{2}}=1;$ x-intercept $=3;$ y-intercept $=2$

69. x-intercept: 6, y-intercept $-4$

71. x-intercept: $-2,$ y-intercept 5

73. $y=x+2;$ because the coordinates of the point $(-1,1)$ satisfy this equation, $(-1,1)$ also lies on this line.

75. $y=-{\displaystyle \frac{3}{4}}x$

77. $y=(3/2)x-4$

79. Parallel

81. Perpendicular

83. Neither

85. Perpendicular

87. Parallel

89. $y=3x-9$

91. $y=2x+4$

93. $y=-x-7$

95. $y=-(1/3)x-5/3$

97. $y=6x+4$

99. $y=-{\displaystyle \frac{1}{6}}x+4$

101. $y=-x+2$

103. $y=-3x-2$