The following representations of rational numbers with respect to the position of the minus sign "\( - \)" are equivalent:
\[\frac{-a}b=\frac a{-b},\quad\quad\frac {-a}{-b}=\frac ab,\quad\quad\frac {0}{-b}=\frac 0b.\]
In particular, it makes sense to put the minus sign in front of the whole ratio:
\[-\frac{a}b:=\frac{-a}b=\frac a{-b}.\]
Moreover, we have \(0=-0\):
\[0=\frac{0}b=-\frac{0}b=-0.\]
Proofs: 1
