Q) Find the equations of the lines parallel to x-axis between which the graph of y=   lies .

A) 

 y=  

This is of the form : | 2ab / (a^2 + b^2) |   where a is 2x and b is 3. And we know: (a - b)^2 > = 0  a^2 + b^2 > = 2ab so | 2ab / (a^2 + b^2) |   < = 1 so y < = 1  and y > = 0    ....(since it is absolute value of something) So the two boundary lines are y = 1 and y = 0 .

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