Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -

Login

Username

Password

Not registered yet?

#1 2008-12-12 01:48:31

ganesh
Moderator

Offline

Logarithms - High school Level

#1. Evaluate

.

#2. If
, find the value of x.

#3. Evaluate :
.

#4. Simpligy:-


#5. Find the value of x which satisfies the relation


#6. Simplify:-


#7. If
, find the number of digits in
.


Character is who you are when no one is looking.
 

#2 2008-12-20 12:44:19

glenn101
Full Member

Offline

Re: Logarithms - High school Level

1.
7^x=1/343
7^x=7^-3
x=-3
2.
root8^x=10/3
x=2log(10/3)
    -------------
    3log(2)
x=1.12
3. I'm assuming you use a calculator, I've never encountered a question like that non-tech.
=2/3
Thats all I got so far:)


"If your going through hell, keep going."
 

#3 2008-12-20 15:48:39

ganesh
Moderator

Offline

Re: Logarithms - High school Level

glenn101,
Solution to the first problem is correct, Good!
Here I have solved two problems for you:-


Character is who you are when no one is looking.
 

#4 2008-12-21 00:29:46

ganesh
Moderator

Offline

Re: Logarithms - High school Level

I shall do #2 and #3 for you, glenn101!

#2. If

, find the value of x.






x = 32.

#3. Evaluate :
.
=

=

=


Character is who you are when no one is looking.
 

#5 2008-12-21 16:47:21

glenn101
Full Member

Offline

Re: Logarithms - High school Level

Thanks for the answers ganesh!
I havn't been taught those sorts of logs before, with surds and same bases.
Looks interesting.
Thanks againup


"If your going through hell, keep going."
 

#6 2008-12-22 03:49:04

careless25
Real Member

Offline

Re: Logarithms - High school Level

glenn have you been taught change of base formula yet?
For number #3 ganesh used that.

 

#7 2008-12-22 12:57:47

glenn101
Full Member

Offline

Re: Logarithms - High school Level

and no I havn't careless, I've only been taught how to deal with same bases, nothing advanced. Next year we deal with e and I'm guessing we will also be taught the change of base formula.


"If your going through hell, keep going."
 

#8 2008-12-23 00:54:58

ganesh
Moderator

Offline

Re: Logarithms - High school Level

glenn101,

The base change formula is very useful.




Character is who you are when no one is looking.
 

#9 2008-12-23 11:59:54

careless25
Real Member

Offline

Re: Logarithms - High school Level

Ganesh i havent been taught that far yet... but for me the base change formula is using base 10 so we can use calculators...

so i always do this:

log 25 (100) = log 10 (100) * log 10 (25)

so always base 10.
but i can see what you mean by that formula and example.

 

#10 2008-12-23 12:05:22

glenn101
Full Member

Offline

Re: Logarithms - High school Level

Hmm that formula looks straightforward and useful!
thanks for that ganesh!up


"If your going through hell, keep going."
 

#11 2008-12-23 15:09:47

ganesh
Moderator

Offline

Re: Logarithms - High school Level

Its a pleasure helping you with logarithms,
logs are such an important tool in calculations!
For my Practical Final-I at University, I had to find the Young's Modulus and this would have been extremely difficult without logarithms or a scientific calculator! We were not allowed to use calculators!


Character is who you are when no one is looking.
 

#12 2008-12-23 15:11:49

careless25
Real Member

Offline

Re: Logarithms - High school Level

Yup my pre-calculus class is heading there...NO CALCULATORS!
except the one in my head! tongue

 

#13 2008-12-23 16:06:56

glenn101
Full Member

Offline

Re: Logarithms - High school Level

Yeah, logs have always been my favorite topic, its easy for me to understand.
Then comes calculus and trig.big_smile


"If your going through hell, keep going."
 

Board footer

Powered by FluxBB