Question

How do you make 3ln2+2ln4 a single logarithm?

Answer 1

3ln 2 = ln 2³ = ln 8
2ln 4 = ln 4² = ln 16
Sum means it is a product:
ln (8 × 16) = ln 128

Or ln (2³×4²)

Answer 2

You can do on this way 
3ln2 + 2ln4 = ln 2^3 + ln 4^2 = ln 8 + ln 16 = ln 128