It just depends but usually it is an inverse for the original equation that you were given
Yes it is a function Bc the x values don’t repeat
27^(4/3)+4^(3/2) can be simplified using roots.
The cube root of 27 is 3 and the square root of 4 is 2. This removes the denominators from the expression. The expression is now 3^4+2^3.
Simplify this and you get 81+8=89