# Math Help - expanding logarithms?

1. ## expanding logarithms?

I think this is called expanding... can someone explain how to work this one, please? TIA... SD

2. Originally Posted by sanddollar
I think this is called expanding... can someone explain how to work this one, please? TIA... SD

Use these two rules:

$log(xy) = log(x) + log(y)$
$log(\frac{x}{y}) = log(x) - log(y)$

3. Here's what I did:

log B + log C/log A + log D

log B + log C - log A - log D

Since the answers are given with log A first, I got
-(log B + log C - log A - log D)

log A - log B - log C + log D

But it says it is not this answer. I can't see what I did wrong

4. What answer does the key provide?

5. Originally Posted by sanddollar
I think this is called expanding... can someone explain how to work this one, please? TIA... SD

$\log\left(\dfrac {BC}{A} \cdot D\right) = \log(B)+\log(C) -\log(A) + \log(D)$
$-\log(A)+\log(B)+\log(C)+\log(D)$