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