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Mathematics 10 Online
OpenStudy (anonymous):

Please help! Problem dealing with logarithms. Click attached

OpenStudy (anonymous):

OpenStudy (anonymous):

You will need to use a few log rules for this. 1. logx-logy=log(x/y) 2. zlogx=log(x^z)

OpenStudy (anonymous):

yeah for this one only these two rules are needed. First try to make all the expressions in the form of log(something)-log(something else).... So get rid of the factors 3, 1/4, 1/2 using the 2. rule

OpenStudy (anonymous):

If thats done you can use the first rule. Good luck! And remember x^(1/2) is equivalent to the square root of x

OpenStudy (anonymous):

Thanks!

OpenStudy (anonymous):

:/ Hmm... I think it's either the second or third but having trouble coming up with the correct final answer

OpenStudy (anonymous):

Let look at it term by term 3logx=?

OpenStudy (anonymous):

1

OpenStudy (anonymous):

1? we dont know what x is, so the solution has to have x in it

OpenStudy (anonymous):

x=1?

OpenStudy (anonymous):

by rule2 3logx=log(x^3)

OpenStudy (anonymous):

we dont know what x is, just imagine any number, but you cannot place!!!! any number there instead of x

OpenStudy (anonymous):

that is called unknown or variable

OpenStudy (anonymous):

so second part 1/4log y=?

OpenStudy (anonymous):

(y is also unknown)

OpenStudy (anonymous):

Yes. But why am I getting y=1? http://www.wolframalpha.com/input/?i=1%2F4logy%3D

OpenStudy (anonymous):

that is its root, different thing It means that when y=1 1/4log y=0 That is called the root of a function, where its value is 0.

OpenStudy (anonymous):

O.k. Now I get it

OpenStudy (anonymous):

wolfram is a good tool but you still need to think

OpenStudy (anonymous):

thats why we have a magical brain! :-)

OpenStudy (anonymous):

:)

OpenStudy (anonymous):

here your only goal is to simplify the log expressions into one log expression

OpenStudy (anonymous):

you are not solving anything, it will be still the same thing just written differently. Some would say in a neater form. (I disagree but that doesnt matter now I guess)

OpenStudy (anonymous):

so 1/4log y=?

OpenStudy (anonymous):

logy/4?

OpenStudy (anonymous):

that is wrong but better than 1 :) rule 2 was: zlogx=log(x^z) In our scenario z is given, it is 1/4 and x should be replaced by y

OpenStudy (anonymous):

log(y^1/4) ?

OpenStudy (anonymous):

Yes, you are getting there!

OpenStudy (anonymous):

1/2logz=?

OpenStudy (anonymous):

1/2log1/4=-/301?

OpenStudy (anonymous):

?

OpenStudy (anonymous):

1/2log1/4 where did this expression come from? Its like a rabbit from a hat

OpenStudy (anonymous):

1/2logz=? where z is unknown, so z should not be replaced by a number!

OpenStudy (anonymous):

I can see that these logs are killing you :D, I dont like them as well....

OpenStudy (anonymous):

AHHHHHH! Yes they are lol Do you mind just going through solving the problem step by step? I'll follow along and can use it as an example

OpenStudy (anonymous):

sure 1/2logz=log(z^1/2)

OpenStudy (anonymous):

so we have 3logx=log(x^3) 1/4logy=log(y^1/4) 1/2logz=log(z^1/2)

OpenStudy (anonymous):

now first two parts logx^3 -logy^1/4 (1. rule)= =log(x^3 /y^1/4)

OpenStudy (anonymous):

log(x^3 /y^1/4) -logz^1/2= (1. rule again) =log){(x^3 /y^1/4) /z^1/2} simplify the middle part now x^3 /y^1/4) /z^1/2= (fraction over fraction is = to 1st fraction multiplied by the reciprocal of the 2nd fraction) =(x^3 /y^1/4) *z^1/2=(x^3*z^1/2)/y^1/4

OpenStudy (anonymous):

so the solution is log(x^3*z^1/2)/y^1/4

OpenStudy (anonymous):

A

OpenStudy (anonymous):

Thank you so very much Andras :) I really appreciate your help and patience haha

OpenStudy (anonymous):

Your welcome, hope it cleared up a bit

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