# Math Help - Subtracting mixed numbers

1. ## Subtracting mixed numbers

When i tried converting the mixed numbers into fractions and subtracting them I got 1 but 1 isn't one of the answer choices. What did I do wrong? The answer key reveal that it's C.

2. ## Re: Subtracting mixed numbers

Originally Posted by asilvester635
When i tried converting the mixed numbers into fractions and subtracting them I got 1 but 1 isn't one of the answer choices. What did I do wrong? The answer key reveal that it's C.
These are NOT mixed numbers. They are EXPONENTIAL numbers.

\displaystyle \begin{align*} 2^{\frac{5}{2}} - 2^{\frac{3}{2}} &= 2\cdot 2^{\frac{3}{2}} - 2^{\frac{3}{2}} \\ &= 2^{\frac{3}{2}} \left( 2 - 1 \right) \\ &= 2^{\frac{3}{2}} \cdot 1 \\ &= 2^{\frac{3}{2}} \end{align*}