logs (c2)

Right, well I'm pretty sure this is a pretty simple c2 logs question but I have tried several ways for it to work and I still can't get the right answer!

The question is:

Log432 - log46 + log412

Help would be greatly appreciated - thank you in advance!

Reply 1

Arsey

10

learn your log rules

log a + log b = log ab

log a - log b = log a/b

these work for any base

so you have

log4(32) + log4(12) - log4(6)

This is combined to give

log4(32*12/6)

log4(64)

you can evaluate this easily on your calc using the log to any base button, on older calculators you would need to say

log4(64) = x

take log4 over to the other side gives

64 = 4^x

x = 3, most of the time the power is obvious, if not log both sides (as in log10 the log button)and solve.

Reply 2

mir3a

13

Original post by em_cart

Right, well I'm pretty sure this is a pretty simple c2 logs question but I have tried several ways for it to work and I still can't get the right answer!

The question is:

Log432 - log46 + log412

Help would be greatly appreciated - thank you in advance!

When you minus logs of the same base, always divide one by the other. When adding, multiply.

Reply 3

em_cart

OP

1

Original post by Arsey

learn your log rules

log a + log b = log ab

log a - log b = log a/b

these work for any base

so you have

log4(32) + log4(12) - log4(6)

This is combined to give

log4(32*12/6)

log4(64)

you can evaluate this easily on your calc using the log to any base button, on older calculators you would need to say

log4(64) = x

take log4 over to the other side gives

64 = 4^x

x = 3, most of the time the power is obvious, if not log both sides (as in log10 the log button)and solve.