• Support PF! Buy your school textbooks, materials and every day products Here!

Finding the power using logarithm

disregardthat
Science Advisor
1,842
33
Actually, I am trying to use what I have learned on school to something else

1. Homework Statement

3*10^x = 1.73*10^14

2. Homework 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:

Answers and Replies

arildno
Science Advisor
Homework Helper
Gold Member
Dearly Missed
9,946
130
Actually, I am trying to use what I have learned on school to something else

1. Homework Statement

3*10^x = 1.73*10^14

2. Homework 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) HOW DID YOU GET YOUR RIGHT-HAND SIDE HERE???
Answer my question, please!
 
disregardthat
Science Advisor
1,842
33
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:
arildno
Science Advisor
Homework Helper
Gold Member
Dearly Missed
9,946
130
Questions:

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

2. Do you see any relevance of 1. to the issue at hand?
 
disregardthat
Science Advisor
1,842
33
I saw the difference, and I got my answer correct.

What do you mean by the number 2. I didn't uderstand :confused:
 
HallsofIvy
Science Advisor
Homework Helper
41,732
893
He was asking you if you saw why that difference was important!
 
disregardthat
Science Advisor
1,842
33
I saw the difference afterwards :)
 

Related Threads for: Finding the power using logarithm

Replies
10
Views
752
  • Last Post
Replies
3
Views
807
  • Last Post
Replies
10
Views
2K
  • Last Post
Replies
22
Views
1K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
5
Views
1K
Replies
16
Views
1K
  • Last Post
Replies
4
Views
2K
Top