# How do you condense #20lna-4lnb#?

##### 1 Answer

#### Answer:

#### Explanation:

Similarly,

So now we have

Now, using the rule

If you like, you can write this as

You can plug numbers in to these rules to make sure they work. For example,

More generally, we can show this rule and the others to be true. I will show that

Start with

Exponentiate both sides to get

Through rules of exponents, the right side can be rewritten to get

Since

To finish, take the natural log of both sides to get

Similar things can be done to prove the other rules true.