# Finding the power using logarithm

1. Jan 28, 2007

### disregardthat

Actually, I am trying to use what I have learned on school to something else

1. The problem statement, all variables and given/known data

3*10^x = 1.73*10^14

2. Relevant equations

lga^x = xlga

3. The attempt at a solution

10^x = (1.73 * 10^14)/3
10^x = 5.767 * 10^13
xlg10 = 13lg(57.67)

x=13lg(57.67)
x=22.89

:\

3 * 10^22.89 = 1.73 * 10^14 is certainly not correct..
What am I doing wrong?

I tried this too:
x=5.767 * 13lg(10)
x=5.767 * 13
x = 74.971

And that is even more incorrect!

Last edited: Jan 28, 2007
2. Jan 28, 2007

### arildno

3. Jan 28, 2007

### disregardthat

i know that if a=b, then lga = lgb
and lga^x=xlga

then i just took the ^13 on the other hand of lg.5.767*10, an made that 13lg5.767*10) and that is 13lg57.67

But if that is incorrect, I tryed it the other way underneath. How am I supposed to get the right answer?

EDIT: I found out the right answer now.

I took the lg(0.576*10^14) and that became 13.76

and 3*10^13,76 is approximately 1.73*10^14

Last edited: Jan 28, 2007
4. Jan 28, 2007

### arildno

Questions:

1. Do you see any difference between the expressions:
$(5.767*10)^{13}$ and $5.767*(10^{13})$?

2. Do you see any relevance of 1. to the issue at hand?

5. Jan 28, 2007

### disregardthat

I saw the difference, and I got my answer correct.

What do you mean by the number 2. I didn't uderstand

6. Jan 29, 2007

### HallsofIvy

Staff Emeritus
He was asking you if you saw why that difference was important!

7. Jan 30, 2007

### disregardthat

I saw the difference afterwards :)