Mathematics - Ellipse Question with Solution | TestHub

For ellipse $\frac{x^2}{16}+\frac{y^2}{9}=1$

Comparing with, standard equation of ellipse $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$, we get  

$a=4,b=3$.

$\therefore e=\sqrt{1-\frac{9}{16}}=\frac{\sqrt{7}}{4}$
Since, $A$ and $B$ are foci

Therefore, $PA+PB=2a$

$=2\times 4=8$.