Question 423875
You need to use the logarithm identity,

{{{log(A/B) = log(A) -log(B)}}}

so,

{{{log((x^2+8x+15))-log((x^2-25))}}}


= {{{log(((x^2+8x+15)/(x^2-25)))}}}


= {{{log(((x^2+3x+5x+15)/(x^2-5^2)))}}}


= {{{log(((x^2+3x)+(5x+15))/(x-5)(x+5)))}}}


= {{{log(((x(x+3)+5(x+3))/(x-5)(x+5)))))}}}


= {{{log((((x+5)(x+3))/(x-5)(x+5))))}}}


= {{{log(((cross((x+5))(x+3))/(x-5)cross((x+5)))))}}}


= {{{log(((x+3)/(x-5)))}}}