Which of the following is the inverse of the function [tex]f(x) = x^3 - 5[/tex]?

A. [tex]f^{-1}(x) = \sqrt[3]{x - 5}[/tex]
B. [tex]f^{-1}(x) = \sqrt[3]{x} + 5[/tex]
C. [tex]f^{-1}(x) = \sqrt[3]{x} - 5[/tex]
D. [tex]f^{-1}(x) = \sqrt[3]{x + 5}[/tex]



Answer :

To determine the inverse of the function [tex]\( f(x) = x^3 - 5 \)[/tex], we must find a function [tex]\( f^{-1}(x) \)[/tex] such that when [tex]\( f(f^{-1}(x)) \)[/tex] and [tex]\( f^{-1}(f(x)) \)[/tex] are applied, we get [tex]\( x \)[/tex] back.

Let's start by setting [tex]\( y = f(x) \)[/tex]:
[tex]\[ y = x^3 - 5 \][/tex]

To find the inverse function, we need to solve for [tex]\( x \)[/tex] in terms of [tex]\( y \)[/tex]:
[tex]\[ y = x^3 - 5 \][/tex]

First, add 5 to both sides to isolate the cubic term:
[tex]\[ y + 5 = x^3 \][/tex]

Next, take the cube root of both sides to solve for [tex]\( x \)[/tex]:
[tex]\[ x = \sqrt[3]{y + 5} \][/tex]

Thus, the inverse function is:
[tex]\[ f^{-1}(x) = \sqrt[3]{x + 5} \][/tex]

So, the correct inverse function of [tex]\( f(x) = x^3 - 5 \)[/tex] is:
[tex]\[ f^{-1}(x) = \sqrt[3]{x + 5} \][/tex]

Among the given options, this matches:
[tex]\[ f^{-1}(x) = \sqrt[3]{x + 5} \][/tex]