Straight Lines And Pair Of Straight Lines

A line is drawn through the point \((1,2)\) to meet the co-ordinate axes at \(\mathrm{P}\) and \(\mathrm{Q}\) such that it forms a \(\triangle \mathrm{OPQ}\), where \(\mathrm{O}\) is the origin. If the area of \(\triangle \mathrm{OPQ}\) is least, then the slope of the line \(\mathrm{PQ}\) is