Solutions to Try Its
1. Focus: (−4,0)(−4,0); Directrix: x=4x=4; Endpoints of the latus rectum: (−4,±8)(−4,±8)
2. Focus: (0,2)(0,2); Directrix: y=−2y=−2; Endpoints of the latus rectum: (±4,2)(±4,2).
3. x2=14yx2=14y
4. x2=14yx2=14y
5. Vertex: (8,−1)(8,−1); Axis of symmetry: y=−1y=−1; Focus: (9,−1)(9,−1); Directrix: x=7x=7; Endpoints of the latus rectum: (9,−3)(9,−3) and (9,1)(9,1).
6. Vertex: (−2,3)(−2,3); Axis of symmetry: x=−2x=−2; Focus: (−2,−2)(−2,−2); Directrix: y=8y=8; Endpoints of the latus rectum: (−12,−2)(−12,−2) and (8,−2)(8,−2).
7. a. y2=1280xy2=1280x
b. The depth of the cooker is 500 mm
Solutions to Odd-Numbered Exercises
1. A parabola is the set of points in the plane that lie equidistant from a fixed point, the focus, and a fixed line, the directrix.
3. The graph will open down.
5. The distance between the focus and directrix will increase.
7. yes y=4(1)x2y=4(1)x2
9. yes (y−3)2=4(2)(x−2)(y−3)2=4(2)(x−2)
11. y2=18x,V:(0,0);F:(132,0);d:x=−132y2=18x,V:(0,0);F:(132,0);d:x=−132
13. x2=−14y,V:(0,0);F:(0,−116);d:y=116x2=−14y,V:(0,0);F:(0,−116);d:y=116
15. y2=136x,V:(0,0);F:(1144,0);d:x=−1144y2=136x,V:(0,0);F:(1144,0);d:x=−1144
17. (x−1)2=4(y−1),V:(1,1);F:(1,2);d:y=0(x−1)2=4(y−1),V:(1,1);F:(1,2);d:y=0
19. (y−4)2=2(x+3),V:(−3,4);F:(−52,4);d:x=−72(y−4)2=2(x+3),V:(−3,4);F:(−52,4);d:x=−72
21. (x+4)2=24(y+1),V:(−4,−1);F:(−4,5);d:y=−7(x+4)2=24(y+1),V:(−4,−1);F:(−4,5);d:y=−7
23. (y−3)2=−12(x+1),V:(−1,3);F:(−4,3);d:x=2(y−3)2=−12(x+1),V:(−1,3);F:(−4,3);d:x=2
25. (x−5)2=45(y+3),V:(5,−3);F:(5,−145);d:y=−165(x−5)2=45(y+3),V:(5,−3);F:(5,−145);d:y=−165
27. (x−2)2=−2(y−5),V:(2,5);F:(2,92);d:y=112(x−2)2=−2(y−5),V:(2,5);F:(2,92);d:y=112
29. (y−1)2=43(x−5),V:(5,1);F:(163,1);d:x=143(y−1)2=43(x−5),V:(5,1);F:(163,1);d:x=143
31.
33.
35.
37.
39.
41.
43.
45. x2=−16yx2=−16y
47. (y−2)2=4√2(x−2)(y−2)2=4√2(x−2)
49. (y+√3)2=−4√2(x−√2)(y+√3)2=−4√2(x−√2)
51. x2=yx2=y
53. (y−2)2=14(x+2)(y−2)2=14(x+2)
55. (y−√3)2=4√5(x+√2)(y−√3)2=4√5(x+√2)
57. y2=−8xy2=−8x
59. (y+1)2=12(x+3)(y+1)2=12(x+3)
61. (0,1)(0,1)
63. At the point 2.25 feet above the vertex.
65. 0.5625 feet
67. x2=−125(y−20)x2=−125(y−20), height is 7.2 feet
69. 2304 feet
Candela Citations
- Precalculus. Authored by: OpenStax College. Provided by: OpenStax. Located at: http://cnx.org/contents/fd53eae1-fa23-47c7-bb1b-972349835c3c@5.175:1/Preface. License: CC BY: Attribution