# Thread: Help with logs: Suppose that u=log10⁡(4) and v=log10⁡(5)....

1. ## Help with logs: Suppose that u=log10⁡(4) and v=log10⁡(5)....

Suppose that u=log10⁡(4) and v=log10⁡(5). Find possible formulas for the following expressions in terms of u and/or v. Your answers should NOT involve any log⁡ 's.
I'm trying to find the log(250) and the log(0.064).
For log(0.064) I tried doing 0.08(u-v), but it wasn't right and I don't know what I did wrong.
For log(250) I tried the square root of u*v^3. It wasn't correct either. I don't know what I'm doing wrong.

2. Originally Posted by megarust
Suppose that u=log10⁡(4) and v=log10⁡(5). Find possible formulas for the following expressions in terms of u and/or v. Your answers should NOT involve any log⁡ 's.
I'm trying to find the log(250) and the log(0.064).
For log(0.064) I tried doing 0.08(u-v), but it wasn't right and I don't know what I did wrong.
For log(250) I tried the square root of u*v^3. It wasn't correct either. I don't know what I'm doing wrong.
Can you show why you thought these might be right? Then we can tell what you did wrong.

I would start by trying to express each number in terms of 4, 5, and 10.

3. Originally Posted by megarust
Suppose that u = log10⁡(4) and v = log10⁡(5). Find possible formulas for the following expressions in terms of u and/or v. Your answers should NOT involve any log⁡ 's.

I'm trying to find the log(250) and the log(0.064).
For log(0.064) I tried doing 0.08(u-v), but it wasn't right and I don't know what I did wrong.
What was your logic for this? Why did you pick this computation? How did you feel that this related to the given expression?

Originally Posted by megarust
For log(250) I tried the square root of u*v^3. It wasn't correct either. I don't know what I'm doing wrong.
Since we have no idea why you're ending up with these expressions, there is no way for us to "know what you're doing wrong". So please reply with that information.

Also, I'm going to guess that you've recently studied log rules (here). Have you considered maybe applying that information? Thank you!