To compute \( \frac{1}{2} - \frac{3}{4} \), we need a common denominator. The least common denominator of 2 and 4 is 4.
Now, we can convert \( \frac{1}{2} \) to have a denominator of 4:
\[ \frac{1}{2} = \frac{1 \times 2}{2 \times 2} = \frac{2}{4} \]
Now we can subtract:
\[ \frac{2}{4} - \frac{3}{4} = \frac{2 - 3}{4} = \frac{-1}{4} \]
Thus, the result is:
\[ \frac{1}{2} - \frac{3}{4} = -\frac{1}{4} \]