not entirely sure what to do... anyone thing they could help?

log4(5-x) - log4(3-x) = 2 x<3

**0**

# Paper 2 2005

Started by laura_lou92, May 20 2009 02:52 PM

3 replies to this topic

### #1

Posted 20 May 2009 - 02:52 PM

### #2

Posted 20 May 2009 - 03:15 PM

QUOTE (laura_lou92 @ May 20 2009, 03:52 PM) <{POST_SNAPBACK}>

not entirely sure what to do... anyone thing they could help?

log4(5-x) - log4(3-x) = 2 x<3

log4(5-x) - log4(3-x) = 2 x<3

Haha i just did this one 5 minutes ago

Right, you already know log_{4}(5-x)-log_{4}(3-x)=2

So you re-arrange to log_{4}(5-x)-log_{4}(3-x)=log_{4}4^2

**Remember**: log_{4}4=1

Then you can cancel out the logs:

(5-x)/(3-x)=4^2

16(3-x)=(5-x)

48-16x=5-x

5-15x=48

-15x=43

x=-43/15

Hope this helped! Any questions just reply back.

Yeah!

### #3

Posted 20 May 2009 - 03:40 PM

QUOTE (Philip @ May 20 2009, 04:15 PM) <{POST_SNAPBACK}>

QUOTE (laura_lou92 @ May 20 2009, 03:52 PM) <{POST_SNAPBACK}>

not entirely sure what to do... anyone thing they could help?

log4(5-x) - log4(3-x) = 2 x<3

log4(5-x) - log4(3-x) = 2 x<3

Haha i just did this one 5 minutes ago

Right, you already know log_{4}(5-x)-log_{4}(3-x)=2

So you re-arrange to log_{4}(5-x)-log_{4}(3-x)=log_{4}4^2

**Remember**: log_{4}4=1

Then you can cancel out the logs:

(5-x)/(3-x)=4^2

16(3-x)=(5-x)

48-16x=5-x

5-15x=48

-15x=43

x=-43/15

Hope this helped! Any questions just reply back.

### #4

Posted 20 May 2009 - 03:44 PM

QUOTE (laura_lou92 @ May 20 2009, 04:40 PM) <{POST_SNAPBACK}>

QUOTE (Philip @ May 20 2009, 04:15 PM) <{POST_SNAPBACK}>

QUOTE (laura_lou92 @ May 20 2009, 03:52 PM) <{POST_SNAPBACK}>

not entirely sure what to do... anyone thing they could help?

log4(5-x) - log4(3-x) = 2 x<3

log4(5-x) - log4(3-x) = 2 x<3

Haha i just did this one 5 minutes ago

Right, you already know log_{4}(5-x)-log_{4}(3-x)=2

So you re-arrange to log_{4}(5-x)-log_{4}(3-x)=log_{4}4^2

**Remember**: log_{4}4=1

Then you can cancel out the logs:

(5-x)/(3-x)=4^2

16(3-x)=(5-x)

48-16x=5-x

5-15x=48

-15x=43

x=-43/15

Hope this helped! Any questions just reply back.

Thank u so much =)

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