College

Determine whether the inverse of \( f \) is a function. If so, then find the inverse.

33. [tex]f(x) = 8x^3[/tex]

34. [tex]f(x) = -x^2 + 3[/tex]

35. [tex]f(x) = x^3 + 4[/tex]

36. [tex]f(x) = 9x^2, \, x \geq 0[/tex]

37. [tex]f(x) = \frac{1}{4}x^2[/tex]

38. [tex]f(x) = \frac{1}{5}x^5[/tex]

39. [tex]f(x) = 2x^2 - 3[/tex]

40. [tex]f(x) = x^4, \, x \geq 0[/tex]

41. [tex]f(x) = 5 - x^3[/tex]

42. [tex]f(x) = x^5 - 2[/tex]

43. [tex]f(x) = x^5 + 1[/tex]

44. [tex]f(x) = 3x^2 - 4[/tex]

45. [tex]f(x) = 9x^2 + 7, \, x \geq 0[/tex]

46. [tex]f(x) = \frac{1}{7}x^3 - 3[/tex]

47. [tex]f(x) = 2x^3 + 2[/tex]

48. [tex]f(x) = 2x^3 - 5[/tex]

49. [tex]f(x) = -x^2, \, x \geq 0[/tex]

50. [tex]f(x) = 16x^4 + 1, \, x \geq 0[/tex]

51. [tex]f(x) = 8x^3 - 6[/tex]

52. [tex]f(x) = 4x^2 - 1[/tex]

53. [tex]f(x) = \frac{1}{2}x^4 - 1, \, x \geq 0[/tex]

Answer :

Sure! Let's analyze each function and determine if its inverse is a function, and if so, find the inverse.

### 33. [tex]\( f(x) = 8x^3 \)[/tex]
The function [tex]\( f(x) = 8x^3 \)[/tex] is a cubic function. Cubic functions are one-to-one, meaning they have inverses that are also functions.

To find the inverse:
1. Start with [tex]\( y = 8x^3 \)[/tex].
2. Solve for [tex]\( x \)[/tex]:
[tex]\[ x = \left(\frac{y}{8}\right)^{1/3} \][/tex]

Thus, the inverse function is:
[tex]\[ f^{-1}(x) = \left(\frac{x}{8}\right)^{1/3} \][/tex]

### 34. [tex]\( f(x) = -x^2 + 3 \)[/tex]
This function is a parabola opening downwards. Parabolic functions do not have inverses that are functions over all values of [tex]\( x \)[/tex] because they are not one-to-one.

Thus, the inverse of this function is not a function.

### 35. [tex]\( f(x) = x^3 + 4 \)[/tex]
The function [tex]\( f(x) = x^3 + 4 \)[/tex] is another cubic function. Like the previous cubic example, this function has an inverse that is also a function.

To find the inverse:
1. Start with [tex]\( y = x^3 + 4 \)[/tex].
2. Solve for [tex]\( x \)[/tex]:
[tex]\[ y - 4 = x^3 \][/tex]
[tex]\[ x = (y - 4)^{1/3} \][/tex]

Thus, the inverse function is:
[tex]\[ f^{-1}(x) = (x - 4)^{1/3} \][/tex]

### 36. [tex]\( f(x) = 9x^2, \, x \geq 0 \)[/tex]
The function [tex]\( f(x) = 9x^2 \)[/tex] with the domain [tex]\( x \geq 0 \)[/tex] is a quadratic function with a restricted domain, making it one-to-one over its domain.

To find the inverse:
1. Start with [tex]\( y = 9x^2 \)[/tex].
2. Solve for [tex]\( x \)[/tex]:
[tex]\[ x = \sqrt{\frac{y}{9}} \][/tex]
Since [tex]\( x \geq 0 \)[/tex], we only take the positive square root.

Thus, the inverse function is:
[tex]\[ f^{-1}(x) = \sqrt{\frac{x}{9}}, \, x \geq 0 \][/tex]

These are the steps to determine the inverses of the functions in the list. Each function is considered individually to see if its inverse can also be a function.