Given:
The function is
[tex]f(x)=\dfrac{8\sqrt[3]{x}-8}{9}[/tex]
To find:
The inverse function [tex]f^{-1}(x)[/tex].
Solution:
We have,
[tex]f(x)=\dfrac{8\sqrt[3]{x}-8}{9}[/tex]
Step 1: Putting f(x)=y, we get
[tex]y=\dfrac{8\sqrt[3]{x}-8}{9}[/tex]
Step 2: Interchange x and y.
[tex]x=\dfrac{8\sqrt[3]{y}-8}{9}[/tex]
Step 3: Isolate variable y.
[tex]9x=8\sqrt[3]{y}-8[/tex]
[tex]9x+8=8\sqrt[3]{y}[/tex]
[tex]\dfrac{9x+8}{8}=\sqrt[3]{y}[/tex]
Taking cube on both sides, we get
[tex]\left(\dfrac{9x+8}{8}\right)^3=y[/tex]
[tex]y=\left(\dfrac{9x+8}{8}\right)^3[/tex]
Step 4: Putting [tex]y=f^{-1}(x)[/tex], we get
[tex]f^{-1}(x)=\left(\dfrac{9x+8}{8}\right)^3[/tex]
Therefore, the correct option is C.
