Step-by-step explanation:
[tex] {f}^{ - 1} (x) = x \: value[/tex]
[tex]f(x) = \sqrt[4]{x} + 6 \\ [/tex]
[tex]x - 6 = \sqrt[4]{x} [/tex]
[tex] {(x - 6)}^{4} = x[/tex]
[tex] {f}^{ - 1}(x) = {(x - 6)}^{4} [/tex]
