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Mathematics 7 Online
rvc (rvc):

Tutorial: Basic Logarithmic Rules

rvc (rvc):

\[\Large1)\ If\ \ a^x=b\ then -->\log_{a} b=x\]

rvc (rvc):

\[\Large\ 2)\ \log_{a} (m.n)=\log_{a}m+\log_{a}n\]

rvc (rvc):

\[\Large\ 3)\log_{a} (m/n)=\log_a{m}-\log_{a}n\]

rvc (rvc):

\(\Large\ 4)\color{green}{Change\ Of\ Base:} \) \[\Large\ A.\log_{a}b=\log_{m}b/\log_{m}a\ (a,b,m>0\ a \neq1)\] \[\Large\ B.\log_{a}b=1/\log_{b}a\ \Large\ OR\ \log_{a}b\ .\ \log_{b}a=1\]

rvc (rvc):

\(\Large\ 5)\color{gold}{The\ Golden\ Rules :}\) \[\Large\color{gold} {A.}\ \color{goldenrod}{\log_{a}1=0\ where\ a>0\ ,\ a \neq1 } \] \[\Large\color{gold} {B.}\ \color{goldenrod}{\log_a{a}=1\ where\ a>0\ ,\ a \neq1}\] \[\Large\color{gold} {C.}\ \color{goldenrod}{a^{\log_{a}x}=x\ where\ a>0\ ,\ a \neq1 }\] \[\Large\color{gold} {D.}\ \color{goldenrod}{\log_{a}m^n=n .\log_{a}m\ where\ m,a>0\ ,\ a \neq1}\]

OpenStudy (michele_laino):

good job!

OpenStudy (anonymous):

I didn't understand number 2 can anyone give some examples?

rvc (rvc):

okay \[\log_{a}(15\ X\ 5)= \log_{a}15+\log_{a}5\]

OpenStudy (anonymous):

I see the little a is what I should be considering as the base?

rvc (rvc):

yeah a is the base here

OpenStudy (anonymous):

I see.. so are there cases where (as you said in rule 2) where we have to find out the base? in cases like that, how do we find the base? :o

rvc (rvc):

normally the base is e in calculus and 10 in other cases Also the base is mentioned if it is not 10 or e

OpenStudy (anonymous):

Oh okay, so can I consider e as constant in calculus? (like I would with Pi ?)

rvc (rvc):

yeah its value is : e=2.71828

OpenStudy (anonymous):

thanks rvc! good job on the tutorial I'm just starting out logarithm so, this is gonna be pretty uselful

rvc (rvc):

Yeah Thank you Hope this helps you @nopen :)

OpenStudy (astrophysics):

Nice one @rvc

OpenStudy (science_ally):

I don't know any of this ..but I will come to you rennyz ^.^

rvc (rvc):

thanks

OpenStudy (anonymous):

And I give you medal

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