Express the given quantity in a single logarithm.

Question

ln(a + b) + ln(a - b) - 2 ln c

Answer 1

The sum of two logarithms is equal to the logarithm of the product, and the difference equals the quotient:
log(A)+log(B)-log(C)
=log(AB/C)

Twice the logarithm of a quantity is the logarithm of the square of the quantity:
2log(C)=log(C²)

So if we put it all together, we get:
log(A)+log(B)-2log(C)
=log( AB/C²)