Задание

Определите знак произведения:

\(\displaystyle a(-b\,)={\bf -ab}\)
\(\displaystyle (-a\,)b={\bf -ab}\)
\(\displaystyle (-a\,)(-b\,)={\bf ab}\)
\(\displaystyle -(-a\,)={\bf a}\)
\(\displaystyle -((-a\,)b\,)={\bf ab}\)
\(\displaystyle -((-a\,)(-b\,))={\bf -ab}\)
\(\displaystyle -(a(-b\,))={\bf ab}\)