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3.3E: Exercises


Practice Makes Perfect

Find an Equation of the Line Given the Slope and y-Intercept

In the following exercises, find the equation of a line with given slope and y-intercept. Write the equation in slope-intercept form.

1. slope $$3$$ and $$y$$-intercept $$(0,5)$$

Answer

$$y=3x+5$$

2. slope $$8$$ and $$y$$-intercept $$(0,−6)$$

3. slope $$−3$$ and $$y$$-intercept $$(0,−1)$$

Answer

$$y=−3x−1$$

4. slope $$−1$$ and $$y$$-intercept $$(0,3)$$

5. slope $$\frac{1}{5}$$ and $$y$$-intercept $$(0,−5)$$

Answer

$$y=\frac{1}{5}x−5$$

6. slope $$−\frac{3}{4}$$ and $$y$$-intercept $$(0,−2)$$

7. slope $$0$$ and $$y$$-intercept $$(0,−1)$$

Answer

$$y=−1$$

8. slope $$−4$$ and $$y$$-intercept $$(0,0)$$

In the following exercises, find the equation of the line shown in each graph. Write the equation in slope-intercept form.

9.

Answer

$$y=3x−5$$

10.

11.

Answer

$$y=\frac{1}{2}x−3$$

12.

13.

Answer

$$y=−\frac{4}{3}x+3$$

14.

15.

Answer

$$y=−2$$

16.

Find an Equation of the Line Given the Slope and a Point

In the following exercises, find the equation of a line with given slope and containing the given point. Write the equation in slope-intercept form.

17. $$m=\frac{5}{8}$$, point $$(8,3)$$

Answer

$$y=\frac{5}{8}x−2$$

18. $$m=\frac{5}{6}$$, point $$(6,7)$$

19. $$m=−\frac{3}{5}$$, point $$(10,−5)$$

Answer

$$y=−\frac{3}{5}x+1$$

20. $$m=−\frac{3}{4}$$, point $$(8,−5)$$

21. $$m=−\frac{3}{2}$$, point $$(−4,−3)$$

Answer

$$y=−\frac{3}{2}x+9$$

22. $$m=−\frac{5}{2}$$, point $$(−8,−2)$$

23. $$m=−7$$, point $$(−1,−3)$$

Answer

$$y=−7x−10$$

24. $$m=−4$$, point $$(−2,−3)$$

25. Horizontal line containing $$(−2,5)$$

Answer

$$y=5$$

26. Horizontal line containing $$(−2,−3)$$

27. Horizontal line containing $$(−1,−7)$$

Answer

$$y=−7$$

28. Horizontal line containing $$(4,−8)$$

Find an Equation of the Line Given Two Points

In the following exercises, find the equation of a line containing the given points. Write the equation in slope-intercept form.

29. $$(2,6)$$ and $$(5,3)$$

Answer

$$y=−x+8$$

30. $$(4,3)$$ and $$(8,1)$$

31. $$(−3,−4)$$ and $$(5−2)$$.

Answer

$$y=\frac{1}{4}x−\frac{13}{4}$$

32. $$(−5,−3)$$ and $$(4,−6)$$.

33. $$(−1,3)$$ and $$(−6,−7)$$.

Answer

$$y=2x+5$$

34. $$(−2,8)$$ and $$(−4,−6)$$.

35. $$(0,4)$$ and $$(2,−3)$$.

Answer

$$y=−\frac{7}{2}x+4$$

36. $$(0,−2)$$ and $$(−5,−3)$$.

37. $$(7,2)$$ and $$(7,−2)$$.

Answer

$$x=7$$

38. $$(−2,1)$$ and $$(−2,−4)$$.

39. $$(3,−4)$$ and $$(5,−4)$$.

Answer

$$y=−4$$

40. $$(−6,−3)$$ and $$(−1,−3)$$

Find an Equation of a Line Parallel to a Given Line

In the following exercises, find an equation of a line parallel to the given line and contains the given point. Write the equation in slope-intercept form.

41. line $$y=4x+2$$, point $$(1,2)$$

Answer

$$y=4x−2$$

42. line $$y=−3x−1$$, point $$2,−3)$$.

43. line $$2x−y=6$$, point $$(3,0)$$.

Answer

$$y=2x−6$$

44. line $$2x+3y=6$$, point $$(0,5)$$.

45. line $$x=−4$$, point $$(−3,−5)$$.

Answer

$$x=−3$$

46. line $$x−2=0$$, point $$(1,−2)$$

47. line $$y=5$$, point $$(2,−2)$$

Answer

$$y=−2$$

48. line $$y+2=0$$, point $$(3,−3)$$

Find an Equation of a Line Perpendicular to a Given Line

In the following exercises, find an equation of a line perpendicular to the given line and contains the given point. Write the equation in slope-intercept form.

49. line $$y=−2x+3$$, point $$(2,2)$$

Answer

$$y=\frac{1}{2}x+1$$

50. line $$y=−x+5$$, point $$(3,3)$$

51. line $$y=\frac{3}{4}x−2$$, point $$(−3,4)$$

Answer

$$y=−\frac{4}{3}x$$

52. line $$y=\frac{2}{3}x−4$$, point $$(2,−4)$$

53. line $$2x−3y=8$$, point $$(4,−1)$$

Answer

$$y=−\frac{3}{2}x+5$$

54. line $$4x−3y=5$$, point $$(−3,2)$$

55. line $$2x+5y=6$$, point $$(0,0)$$

Answer

$$y=\frac{5}{2}x$$

56. line $$4x+5y=−3$$, point $$(0,0)$$

57. line $$x=3$$, point $$(3,4)$$

Answer

$$y=4$$

58. line $$x=−5$$, point $$(1,−2)$$

59. line $$x=7$$, point $$(−3,−4)$$

Answer

$$y=−4$$

60. line $$x=−1$$, point $$(−4,0)$$

61. line $$y−3=0$$, point $$(−2,−4)$$

Answer

$$x=−2$$

62. line $$y−6=0$$, point $$(−5,−3)$$

63. line $$y$$-axis, point $$(3,4)$$

Answer

$$y=4$$

64. line $$y$$-axis, point $$(2,1)$$

Mixed Practice

In the following exercises, find the equation of each line. Write the equation in slope-intercept form.

65. Containing the points $$(4,3)$$ and $$(8,1)$$

Answer

$$y=−\frac{1}{2}x+5$$

66. Containing the points $$(−2,0)$$ and $$(−3,−2)$$

67. $$m=\frac{1}{6}$$, containing point $$(6,1)$$

Answer

$$y=\frac{1}{6}x$$

68. $$m=\frac{5}{6}$$, containing point $$(6,7)$$

69. Parallel to the line $$4x+3y=6$$, containing point $$(0,−3)$$

Answer

$$y=−\frac{4}{3}x−3$$

70. Parallel to the line $$2x+3y=6$$, containing point $$(0,5)$$

71. $$m=−\frac{3}{4}$$, containing point $$(8,−5)$$

Answer

$$y=−\frac{3}{4}x+1$$

72. $$m=−\frac{3}{5}$$, containing point $$(10,−5)$$

73. Perpendicular to the line $$y−1=0$$, point $$(−2,6)$$

Answer

$$x=−2$$

74. Perpendicular to the line y-axis, point $$(−6,2)$$

75. Parallel to the line $$x=−3$$, containing point $$(−2,−1)$$

Answer

$$x=−2$$

76. Parallel to the line $$x=−4$$, containing point $$(−3,−5)$$

77. Containing the points $$(−3,−4)$$ and $$(2,−5)$$

Answer

$$y=−\frac{1}{5}x−\frac{23}{5}$$

78. Containing the points $$(−5,−3)$$ and $$(4,−6)$$

79. Perpendicular to the line $$x−2y=5$$, point $$(−2,2)$$

Answer

$$y=−2x−2$$

80. Perpendicular to the line $$4x+3y=1$$, point $$(0,0)$$

Writing Exercises

81. Why are all horizontal lines parallel?

Answer

Answers will vary.

82. Explain in your own words why the slopes of two perpendicular lines must have opposite signs.

Self Check

a. After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.

b. What does this checklist tell you about your mastery of this section? What steps will you take to improve?

This page titled 3.3E: Exercises is shared under a CC BY license and was authored, remixed, and/or curated by OpenStax.

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