BTGmoderatorDC wrote:If b is positive, is ab positive?
$$\left(1\right)\ a^2b\ >0$$
$$\left(2\right)\ a^2\ +\ b\ =\ 13$$
\[b > 0\]
\[ab\,\,\mathop > \limits^? \,\,0\]
\[\left( {1 + 2} \right)\,\,\left\{ \begin{gathered}
\,Take\,\,\,\left( {a,b} \right) = \left( {1,12} \right)\,\,\,\,\,\, \Rightarrow \,\,\,\,\left\langle {{\text{YES}}} \right\rangle \hfill \\
\,Take\,\,\,\left( {a,b} \right) = \left( { - 1,12} \right)\,\,\,\,\,\, \Rightarrow \,\,\,\,\left\langle {{\text{NO}}} \right\rangle \hfill \\
\end{gathered} \right.\]
The above follows the notations and rationale taught in the GMATH method.
