The domain of f(x)=cosx must be restricted to all real numbers in order for the function to have an inverse function. The domain of g(x)=arccos(x)
is −1≤x≤1
and its range is 0≤x≤π
.
is this correct ?

if you think it is and if your positive and if you know what your doing then yes its correct

hope this helps :) have a nice day

Step-by-step explanation:

Not completely sure for the rest, but I believe the range is incorrect: the range represents y-values, not x-values.

So it should be 0 ≤ x ≤ π

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation:

step-by-step explanation: