For f(x)=log3log5log7(9x−x2−13):
log7(⋅)>0⇒9x−x2−13>1⇒(x−2)(x−7)<0⇒x∈(2,7).
log5(⋅)>0⇒log7(9x−x2−13)>1⇒9x−x2−13>7⇒(x−4)(x−5)<0⇒x∈(4,5).
Domain =(4,5), so m=4,n=5.
Eccentricity e=n/3=5/3, latus rectum =8m/3=32/3.
e2=1+b2/a2⇒b2/a2=16/9.
2b2/a=32/3⇒32a/9=32/3⇒a=3, so a2=9, b2=16.
b2−a2=16−9=7.