Answer
$x^{1/4}(\sqrt x - 1)$
Work Step by Step
To simplify, factor the first term at the smallest exponent $x^{1/4}.$
This is the greatest common factor. So,
$x^{3/4} - x^{1/4} = x^{1/4}. x^{1/2} - x^{1/4}$
Factor out the greatest common factor
$=x^{1/4}( x^{1/2} - 1)$
$=x^{1/4}( \sqrt x - 1)$
