## Algebra: A Combined Approach (4th Edition)

-$\frac{a}{b}$ = $\frac{-a}{b}$ = $\frac{a}{-b}$
We know (-1)$\frac{a}{b}$ = $\frac{-a}{b}$. Also, $\frac{-a}{b}$ = $\frac{a}{-b}$. To see this, cross multiply. (-a)(-b) = (a)(b)? ab = ab ....... (Since (-1)(-1) = 1).