Answer
$x^{\frac{1}{4}}(x^{\frac{1}{2}}-1)$
Work Step by Step
$x^{\frac{3}{4}}=x^{\frac{1}{4}+\frac{2}{4}}=x^{\frac{1}{4}}\cdot x^{\frac{1}{2}}$
$ x^{\frac{3}{4}}-x^{\frac{1}{4}}=x^{\frac{1}{4}}\cdot x^{\frac{1}{2}}-x^{\frac{1}{4}}\qquad$... factor out $x^{\frac{1}{4}}$
=$x^{\frac{1}{4}}(x^{\frac{1}{2}}-1)$