a natural log problem

use properties of lograithms to expand:

ln [(x^2 -16) / (x^4)] , x>4

=ln (x^2-16)- ln x^4
=ln (x-4)(x+4) - 4lnx
=ln(x-4) + ln(x+4) - 4lnx

******************************************************
write this as a logarithm of a single quantity:

2 ln x- (1/2) ln (X+5)

= ln x^2 - ln(x+5) ^ (1/2)
=ln[ (x^2) / (x+5)^(1/2) ]
=ln [x^2 *(x+5)^(1/2)/(x+5)]

2009-02-19 15:24:43 補充：
ln (x-4)(x+4) - 4lnx should change to :

In[(x-4)(x+4)] - 4lnx