



 
H Sophia, Is l a particular line or you do this for any line? Sophia write back
Sometimes when answering a math question it helps to experiment a little. Suppose the line is the Xaxis. Every point on the Xaxis has coordinates $(x,0)$ for some real number $x$ so the product of the $x$ and $y$ coordinates is zero which satisfies "the product of the xcoordinate and the ycoordinate is less than or equal to zero". Suppose the line is the Yaxis. Every point on the Yaxis has coordinates $(0,y)$ for some real number $y$ so the product of the $x$ and $y$ coordinates is zero which satisfies "the product of the xcoordinate and the ycoordinate is less than or equal to zero". Now consider the lines $y = x$ and $y = x.$ Take a few points on each of the lines and calculate the product of the $x$ and $y$ coordinates of each of the points you selected. Penny  


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