If e1 is the eccentricity of the conic 9x2 + 4y2 = 36 and e2 is the eccentricity of the conic 9x2 – 4y2 = 36, then

Given: e1 and e2 are respectively the eccentricities of 9x2 + 4y2 = 36 and 9x2 – 4y2 = 36 respectively


To find: e12 – e22


9x2 – 4y2 = 36





Eccentricity(e) of hyperbola is given by,



Here a = 2 and b = 3





Therefore,



For ellipse:


9x2 + 4y2 = 36





Eccentricity(e) of ellipse is given by,



Here a = 2 and b = 3





Therefore,



Substituting values from (1) and (2) in 2e12 + e22


e12 – e22






e22 – e22



Hence, value of 2 < e22 – e12 < 3

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