# How do you evaluate 2^(5/2) - 2^(3/2)?

${x}^{\frac{m}{n}} = \sqrt[n]{{x}^{m}}$ so you get:
$\sqrt{{2}^{5}} - \sqrt{{2}^{3}} = \sqrt{{2}^{2} \cdot {2}^{2} \cdot 2} - \sqrt{{2}^{2} \cdot 2} =$
you can take out from the roots as many ${2}^{2}$ you can ($\sqrt{{2}^{2}} = 2$):
$= {2}^{2} \sqrt{2} - 2 \sqrt{2} =$
$= \sqrt{2} \left[4 - 2\right] = 2 \sqrt{2}$