1. **Problem:** Find the domain and critical values of the function $$y = x^3 + 6x^2 + 12x - 1$$.
2. **Domain:** Since this is a polynomial, the domain is all real numbers, $$\mathbb{R}$$.
3. **Find the derivative:**
$$y' = 3x^2 + 12x + 12$$
4. **Set derivative equal to zero to find critical points:**
$$3x^2 + 12x + 12 = 0$$
5. **Divide entire equation by 3:**
$$\cancel{3}x^2 + \cancel{3}4x + \cancel{3}4 = 0 \Rightarrow x^2 + 4x + 4 = 0$$
6. **Factor the quadratic:**
$$ (x + 2)^2 = 0 $$
7. **Solve for x:**
$$ x = -2 $$
8. **Critical value:** Substitute back into original function:
$$ y(-2) = (-2)^3 + 6(-2)^2 + 12(-2) - 1 = -8 + 24 - 24 - 1 = -9 $$
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9. **Problem:** Find the domain and critical values of $$y = x^5 + 5x^4 - 5x^3 - 35x^2 - 40x - 1$$.
10. **Domain:** All real numbers, $$\mathbb{R}$$.
11. **Derivative:**
$$ y' = 5x^4 + 20x^3 - 15x^2 - 70x - 40 $$
12. **Set derivative to zero:**
$$ 5x^4 + 20x^3 - 15x^2 - 70x - 40 = 0 $$
13. **Divide by 5:**
$$ \cancel{5}x^4 + \cancel{5}4x^3 - \cancel{5}3x^2 - \cancel{5}14x - \cancel{5}8 = 0 \Rightarrow x^4 + 4x^3 - 3x^2 - 14x - 8 = 0 $$
14. **Solve quartic equation (numerical or factoring methods needed).**
---
15. **Problem:** Find the domain and critical values of $$y = 4x^3 - 21x^2 + 48x - 7$$.
16. **Domain:** All real numbers, $$\mathbb{R}$$.
17. **Derivative:**
$$ y' = 12x^2 - 42x + 48 $$
18. **Set derivative to zero:**
$$ 12x^2 - 42x + 48 = 0 $$
19. **Divide by 6:**
$$ \cancel{6}2x^2 - \cancel{6}7x + \cancel{6}8 = 0 \Rightarrow 2x^2 - 7x + 8 = 0 $$
20. **Calculate discriminant:**
$$ \Delta = (-7)^2 - 4 \cdot 2 \cdot 8 = 49 - 64 = -15 < 0 $$
21. **No real roots, so no critical points.**
---
22. **Problem:** Find the domain and critical values of $$y = x^4 - 32x^2 + 12$$.
23. **Domain:** All real numbers, $$\mathbb{R}$$.
24. **Derivative:**
$$ y' = 4x^3 - 64x $$
25. **Set derivative to zero:**
$$ 4x^3 - 64x = 0 $$
26. **Factor out 4x:**
$$ 4x(x^2 - 16) = 0 $$
27. **Set each factor to zero:**
$$ 4x = 0 \Rightarrow x = 0 $$
$$ x^2 - 16 = 0 \Rightarrow x = \pm 4 $$
28. **Critical points:**
$$ x = -4, 0, 4 $$
29. **Find corresponding y-values:**
$$ y(-4) = (-4)^4 - 32(-4)^2 + 12 = 256 - 512 + 12 = -244 $$
$$ y(0) = 0 - 0 + 12 = 12 $$
$$ y(4) = 256 - 512 + 12 = -244 $$
---
30. **Problem:** Find the domain and critical values of $$y = 3x^5 - 40x^3 + 180x - 71$$.
31. **Domain:** All real numbers, $$\mathbb{R}$$.
32. **Derivative:**
$$ y' = 15x^4 - 120x^2 + 180 $$
33. **Set derivative to zero:**
$$ 15x^4 - 120x^2 + 180 = 0 $$
34. **Divide by 15:**
$$ \cancel{15}x^4 - \cancel{15}8x^2 + \cancel{15}12 = 0 \Rightarrow x^4 - 8x^2 + 12 = 0 $$
35. **Substitute $$u = x^2$$:**
$$ u^2 - 8u + 12 = 0 $$
36. **Solve quadratic:**
$$ u = \frac{8 \pm \sqrt{64 - 48}}{2} = \frac{8 \pm \sqrt{16}}{2} = \frac{8 \pm 4}{2} $$
37. **Solutions for u:**
$$ u_1 = 6, u_2 = 2 $$
38. **Back-substitute:**
$$ x^2 = 6 \Rightarrow x = \pm \sqrt{6} $$
$$ x^2 = 2 \Rightarrow x = \pm \sqrt{2} $$
39. **Critical points:**
$$ x = \pm \sqrt{6}, \pm \sqrt{2} $$
40. **Find y-values by substitution (optional).**
---
41. **Problem:** Find the domain and critical values of $$y = x^3 + x^2 - 5x - 3$$ on $$x \in [-3,1]$$.
42. **Domain:** Closed interval $$[-3,1]$$.
43. **Derivative:**
$$ y' = 3x^2 + 2x - 5 $$
44. **Set derivative to zero:**
$$ 3x^2 + 2x - 5 = 0 $$
45. **Calculate discriminant:**
$$ \Delta = 2^2 - 4 \cdot 3 \cdot (-5) = 4 + 60 = 64 $$
46. **Solve for x:**
$$ x = \frac{-2 \pm 8}{6} $$
47. **Solutions:**
$$ x_1 = 1, x_2 = -\frac{5}{3} \approx -1.6667 $$
48. **Both critical points are in the domain.**
49. **Evaluate y at critical points and endpoints:**
$$ y(1) = 1 + 1 - 5 - 3 = -6 $$
$$ y(-\frac{5}{3}) = (-\frac{5}{3})^3 + (-\frac{5}{3})^2 - 5(-\frac{5}{3}) - 3 = -\frac{125}{27} + \frac{25}{9} + \frac{25}{3} - 3 = \frac{256}{27} \approx 9.48 $$
$$ y(-3) = -27 + 9 + 15 - 3 = -6 $$
---
50. **Problem:** Find the domain and critical values of $$y = 2x^3 + x^2 - 4x + 8$$ on $$x \in [0,7]$$.
51. **Domain:** Closed interval $$[0,7]$$.
52. **Derivative:**
$$ y' = 6x^2 + 2x - 4 $$
53. **Set derivative to zero:**
$$ 6x^2 + 2x - 4 = 0 $$
54. **Divide by 2:**
$$ 3x^2 + x - 2 = 0 $$
55. **Calculate discriminant:**
$$ \Delta = 1^2 - 4 \cdot 3 \cdot (-2) = 1 + 24 = 25 $$
56. **Solve for x:**
$$ x = \frac{-1 \pm 5}{6} $$
57. **Solutions:**
$$ x_1 = \frac{4}{6} = \frac{2}{3} \approx 0.6667, x_2 = -1 $$
58. **Only $$x=\frac{2}{3}$$ is in the domain.**
59. **Evaluate y at critical point and endpoints:**
$$ y(0) = 8 $$
$$ y(\frac{2}{3}) = 2(\frac{2}{3})^3 + (\frac{2}{3})^2 - 4(\frac{2}{3}) + 8 = 2(\frac{8}{27}) + \frac{4}{9} - \frac{8}{3} + 8 = \frac{16}{27} + \frac{12}{27} - \frac{72}{27} + \frac{216}{27} = \frac{172}{27} \approx 6.37 $$
$$ y(7) = 2(343) + 49 - 28 + 8 = 686 + 49 - 28 + 8 = 715 $$
---
60. **Problem:** Find the domain and critical values of $$y = -3x^4 + 24x^2 + 5$$ on $$x \in [-3,5]$$.
61. **Domain:** Closed interval $$[-3,5]$$.
62. **Derivative:**
$$ y' = -12x^3 + 48x $$
63. **Set derivative to zero:**
$$ -12x^3 + 48x = 0 $$
64. **Factor:**
$$ -12x(x^2 - 4) = 0 $$
65. **Solve:**
$$ x = 0, x = \pm 2 $$
66. **All critical points are in the domain.**
67. **Evaluate y at critical points and endpoints:**
$$ y(-3) = -3(81) + 24(9) + 5 = -243 + 216 + 5 = -22 $$
$$ y(-2) = -3(16) + 24(4) + 5 = -48 + 96 + 5 = 53 $$
$$ y(0) = 5 $$
$$ y(2) = 53 $$
$$ y(5) = -3(625) + 24(25) + 5 = -1875 + 600 + 5 = -1270 $$
---
68. **Problem:** Find the domain and critical values of $$y = 2x^5 - 35x^3 + 135x - 29$$ on $$x \in [-2,6]$$.
69. **Domain:** Closed interval $$[-2,6]$$.
70. **Derivative:**
$$ y' = 10x^4 - 105x^2 + 135 $$
71. **Set derivative to zero:**
$$ 10x^4 - 105x^2 + 135 = 0 $$
72. **Divide by 5:**
$$ 2x^4 - 21x^2 + 27 = 0 $$
73. **Substitute $$u = x^2$$:**
$$ 2u^2 - 21u + 27 = 0 $$
74. **Calculate discriminant:**
$$ \Delta = (-21)^2 - 4 \cdot 2 \cdot 27 = 441 - 216 = 225 $$
75. **Solve for u:**
$$ u = \frac{21 \pm 15}{4} $$
76. **Solutions:**
$$ u_1 = 9, u_2 = 1.5 $$
77. **Back-substitute:**
$$ x^2 = 9 \Rightarrow x = \pm 3 $$
$$ x^2 = 1.5 \Rightarrow x = \pm \sqrt{1.5} \approx \pm 1.2247 $$
78. **Critical points in domain:** $$-2 \leq x \leq 6$$ includes $$-3$$ is outside domain, so discard.
79. **Valid critical points:** $$x = -1.2247, 1.2247, 3$$
---
80. **Problem:** Find the domain and extreme points of $$y = x^5 - 16x + 12$$.
81. **Domain:** All real numbers, $$\mathbb{R}$$.
82. **Derivative:**
$$ y' = 5x^4 - 16 $$
83. **Set derivative to zero:**
$$ 5x^4 - 16 = 0 \Rightarrow 5x^4 = 16 \Rightarrow x^4 = \frac{16}{5} $$
84. **Solve for x:**
$$ x = \pm \sqrt[4]{\frac{16}{5}} = \pm \left(\frac{16}{5}\right)^{1/4} $$
85. **Extreme points at these x-values.**
---
86. **Problem:** Find the domain and extreme points of $$y = 2x^3 + 9x^2 - 168x$$.
87. **Domain:** All real numbers, $$\mathbb{R}$$.
88. **Derivative:**
$$ y' = 6x^2 + 18x - 168 $$
89. **Set derivative to zero:**
$$ 6x^2 + 18x - 168 = 0 $$
90. **Divide by 6:**
$$ x^2 + 3x - 28 = 0 $$
91. **Calculate discriminant:**
$$ \Delta = 3^2 - 4 \cdot 1 \cdot (-28) = 9 + 112 = 121 $$
92. **Solve for x:**
$$ x = \frac{-3 \pm 11}{2} $$
93. **Solutions:**
$$ x_1 = 4, x_2 = -7 $$
---
94. **Problem:** Find the domain and extreme points of $$y = x^4 - 6x^2 - 12$$ on $$x \in [-1,2]$$.
95. **Domain:** Closed interval $$[-1,2]$$.
96. **Derivative:**
$$ y' = 4x^3 - 12x $$
97. **Set derivative to zero:**
$$ 4x^3 - 12x = 0 $$
98. **Factor:**
$$ 4x(x^2 - 3) = 0 $$
99. **Solve:**
$$ x = 0, x = \pm \sqrt{3} $$
100. **Only $$x=0$$ is in domain.**
101. **Evaluate y at critical point and endpoints:**
$$ y(-1) = 1 - 6 - 12 = -17 $$
$$ y(0) = 0 - 0 - 12 = -12 $$
$$ y(2) = 16 - 24 - 12 = -20 $$
---
102. **Problem:** Find the domain and extreme points of $$y = 3x^3 + 2x^2 - 27x - 18$$ on $$x \in [-3,3)$$.
103. **Domain:** Half-open interval $$[-3,3)$$.
104. **Derivative:**
$$ y' = 9x^2 + 4x - 27 $$
105. **Set derivative to zero:**
$$ 9x^2 + 4x - 27 = 0 $$
106. **Calculate discriminant:**
$$ \Delta = 4^2 - 4 \cdot 9 \cdot (-27) = 16 + 972 = 988 $$
107. **Solve for x:**
$$ x = \frac{-4 \pm \sqrt{988}}{18} $$
108. **Approximate roots:**
$$ x_1 \approx 1.56, x_2 \approx -1.92 $$
109. **Both roots are in domain.**
---
110. **Problem:** Find the domain and range of $$y = x^2 + 5x - 7$$.
111. **Domain:** All real numbers, $$\mathbb{R}$$.
112. **Find vertex (minimum or maximum):**
$$ x = -\frac{b}{2a} = -\frac{5}{2} = -2.5 $$
113. **Evaluate y at vertex:**
$$ y(-2.5) = (-2.5)^2 + 5(-2.5) - 7 = 6.25 - 12.5 - 7 = -13.25 $$
114. **Since $$a=1 > 0$$, parabola opens upward, so minimum is $$-13.25$$. Range is $$[-13.25, \infty)$$.
---
115. **Problem:** Find the domain and range of $$y = 3x^4 + 2x^3 + 12x^2 + 12x - 42$$.
116. **Domain:** All real numbers, $$\mathbb{R}$$.
117. **Since $$x^4$$ dominates and coefficient is positive, $$y \to \infty$$ as $$|x| \to \infty$$.
118. **Find critical points by derivative:**
$$ y' = 12x^3 + 6x^2 + 24x + 12 $$
119. **Set derivative to zero:**
$$ 12x^3 + 6x^2 + 24x + 12 = 0 $$
120. **Divide by 6:**
$$ 2x^3 + x^2 + 4x + 2 = 0 $$
121. **Solve cubic (numerical or factoring needed) to find critical points and evaluate y to find minimum/maximum for range.**
Domain Critical Values 2E5E11
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