What is the domain of #f(x)=sqrt{1-sqrt[1-sqrt(1-x^2)]}# ?

1 Answer
Dec 15, 2017

The domain of #f(x)# is #[-1, 1]# and its range is #[0, 1]#

Explanation:

Given:

#f(x) = sqrt(1-sqrt(1-sqrt(1-x^2)))#

Note that the square of any real number is non-negative. So #sqrt(t)# only has real values for #t >= 0#

So #sqrt(1-x^2)# is only defined as a real valued square root if:

#1-x^2 >= 0#

Note that if #x# is real then #x^2 >= 0#. Hence the range of values for which #1-x^2 >= 0# is #x in [-1, 1]#.

Suppose #x in [-1, 1]#. Then:

  • #x^2 in [0, 1]#

  • #1 - x^2 in [0, 1]#

  • #sqrt(1-x^2) in [0, 1]#

  • #1 - sqrt(1-x^2) in [0, 1]#

  • #sqrt(1-sqrt(1-x^2)) in [0, 1]#

  • #1-sqrt(1-sqrt(1-x^2)) in [0, 1]#

  • #sqrt(1-sqrt(1-sqrt(1-x^2))) in [0, 1]#

So the domain of #f(x)# is #[-1, 1]# and its range is #[0, 1]#