(-2log²5 15 - log²5 9 + 3*log5 15* log5 9)/(log5 9-log5 15) =
(-(log²5 15 - 2*log5 15* log5 9 + log²5 9) + log5 15* log5 9 - log²5 15 )/(log5 9-log5 15) =
(-(log5 9 - log5 15)² + log5 15 (log5 9 - log5 15) )/(log5 9-log5 15) =
(log5 9 - log5 15)( log5 15 - (log5 9 - log5 15) )/(log5 9-log5 15) =
log5 15 - log5 9 + log5 15 = log5 (15*15)/9 = log5 (5²3²)/9 = log5 5² = 2
(-2log²5 15 - log²5 9 + 3*log5 15* log5 9)/(log5 9-log5 15) =
(-(log²5 15 - 2*log5 15* log5 9 + log²5 9) + log5 15* log5 9 - log²5 15 )/(log5 9-log5 15) =
(-(log5 9 - log5 15)² + log5 15 (log5 9 - log5 15) )/(log5 9-log5 15) =
(log5 9 - log5 15)( log5 15 - (log5 9 - log5 15) )/(log5 9-log5 15) =
log5 15 - log5 9 + log5 15 = log5 (15*15)/9 = log5 (5²3²)/9 = log5 5² = 2