Does any Know how to change the base of a log on a scientific cal.?

Question

okay.. so the problem states -log(base 1/3) X and i don't know how to change it from base 10 to base 1/3

Answer 1

log(base a) b = logb/loga.

So take the log of X and divide by the log of 1/3. Then press the +/- button because you're being asked for the negative of that value.

Answer 2

you can't - on any calculator, it's always base 10. You need the change of base formula:

log(base b)A=

log(any base you want) A
---------------------------------
log(same as above) b

example:

log(base 1/3) X

I want base 10 - for calc.:

log(base 10) X
------------------ <-denotes division
log(base 10) 1/3

I want base 3 -> solve without calc: ex: log(base 1/3) 3

log(base 3) 3 1
---------------- = ----- = -1
log(base 3) 1/3 -1