Question

The eccentricity of the ellipse $12x^2+7y^2=84$ is equal to

• A. $\frac{\sqrt{5}}{7}$
• B. $\sqrt{\frac{5}{12}}$
• C. $\frac{\sqrt{5}}{12}$
• D. $\sqrt{\frac{5}{7}}$

Answer 1

The correct option is B

$\sqrt{\frac{5}{12}}$

$12x^2+7y^2=84\frac{x^2}{7}+\frac{y^2}{12}=1a^2=7;b^2=12Focallength,c=\sqrt{b^2-a^2}c=\sqrt{12-7}=\sqrt{5}e=\frac{c}{a}=\sqrt{\frac{5}{12}}$