## Elementary Technical Mathematics

$-\displaystyle \frac{1}{2}$
Apply the equivalent fractions rule, $\quad \displaystyle \frac{a}{-b}=\frac{-a}{b}=-\frac{a}{b}$ $\displaystyle \frac{-1}{-4}=-\frac{1}{-4}=-(-\frac{1}{4})=+\frac{1}{4}$ So, the problem becomes $=\displaystyle \left(-\frac{2}{1} \right) \cdot\left(+\frac{1}{4} \right)$ Multiplying two numbers with different signs: Multiply their absolute values; the sign of the result is "$-$". $=-\displaystyle \left(\frac{2}{1}\cdot\frac{1}{4} \right)$ Multiply fractions: Reduce by the common factor, 2. $=-\displaystyle \left(\frac{1}{1}\cdot\frac{1}{2} \right)$ Now, multiply the numerators and place them over the product of the denominators. $=-\displaystyle \frac{1}{2}$