Exponential

Quote:

3 to the power of x equals 30. how to solve?

3 ^x=30

take logs of both sides

x log(3) = log(30)

x = log(30)/log(3) = log(3*10)/log(3) = (log(3)+log(10))/log(3) = 1 + 1/log(3)

3 ^x=30

I just want to stress the first step

log 3 ^x= log 30

but log 3 ^x = xlog3
that is how Rom got

xlog3 = log 30

This is a handy page to keep nearby when you are dealing with logs although eventually you will need to memorise all the identities.

http://en.wikipedia.org/wiki/List_of_logarithmic_identities

Melody:

3^x=30

I...
This is a handy page to keep nearby when you are dealing with logs although eventually you will need to memorise all the identities.

http://en.wikipedia.org/wiki/List_of_logarithmic_identities

Also, this site has lots of useful identities listed. Just select Formulary from the ribbon at the top of the page.

Thank you Alan, I didn't realise that they were there.