Thread: Log and nl stuff

I keep on getting these wrong and I don't know what am I doing wrong for these problems:

1. 1/3ln3 + 2ln3
I first moved 1/3 and the equation becomes ln3^1/3 + ln3^2, after that I combined them and it becomes ln3^7/3. And that last step is where I was marked wrong.

2. ln20 - ln5 - 2/3ln8
I boiled down to ln4 - ln4 and after that I wrote 1 as final answer. It was marked wrong but I thought subtraction in ln means division?

Originally Posted by windia

1. 1/3ln3 + 2ln3
I first moved 1/3 and the equation becomes ln3^1/3 + ln3^2, after that I combined them and it becomes ln3^7/3. And that last step is where I was marked wrong.

Correct. But perhaps you were required to write it in the form ?

[2. ln20 - ln5 - 2/3ln8
I boiled down to ln4 - ln4 and after that I wrote 1 as final answer. It was marked wrong but I thought subtraction in ln means division?

That's right. But when you perform the division, you get . Now, what's ?

Ahh I see lol

Originally Posted by windia

I keep on getting these wrong and I don't know what am I doing wrong for these problems:

1. 1/3ln3 + 2ln3
I first moved 1/3 and the equation becomes ln3^1/3 + ln3^2, after that I combined them and it becomes ln3^7/3. And that last step is where I was marked wrong.

2. ln20 - ln5 - 2/3ln8
I boiled down to ln4 - ln4 and after that I wrote 1 as final answer. It was marked wrong but I thought subtraction in ln means division?

to #1: Your calculations seem to be OK, but your notation is horrible. Actually you should write the result as: ln(3^(7/3)).

to #2: This term is quite ambiguous. You have to use brackets to be clear:

(ln(20) - ln(5)) - 2/3ln(8) =

ln(20) - (ln(5) - 2/3ln(8)) =

Originally Posted by windia

I boiled down to ln4 - ln4 and after that I wrote 1 as final answer. It was marked wrong but I thought subtraction in ln means division?

Did you forget that ?