Rewriting expressions to logarithms?

Question

Rewrite the expression

f(x)= ln ( x^2-25/x^4)

using properties of logarithms

Answer 1

f(x) = ln (x^2-25/x^4)

lna/b = lna-lnb and lnab = lna+lnb

= ln (x^2-25) -ln (x^4)

= ln ((x+5)(x-5))- 4 ln x

= ln (x+5)+ ln (x-5) - 4 ln x