How do you write ln(x23x40)1n(x8) as a single logarithm?

1 Answer
Feb 12, 2015

Remember than ln(ab)=lnalnb

But now we do this the other way around:

ln(x23x40)ln(x8)=

ln(x23x40x8)=

We can factorise the top part:

ln((x8)(x+5)(x8))=

Cancel out the (x8)'s

Answer:

ln(x+5)

Extra :
Domain : x>8
(or else the original ln(x8) would be invalid)