Let
I=∫59log3x2+log(588−84x+3x2)log3x2dx...(i)
=∫59log3x2+log3(14−x)2log3x2dx=∫59log3(14−x)2+log3(14−(14−x))2log3(14−x)2dx[∫abf(x)dx=∫abf(a+b−x)dx]I=\int_5^9 \frac{\log 3(14-x)^2 d x}{\log 3(14-x)^2+\log 3 x^2}
...(ii)AddingEqs.(i)and(ii),weget2I=∫59log3(14−x)2+log3x2log3x2+log3(14−x)2dx2I=∫59dx=9−5=4⇒I=2$