Tips for evaluating logs without a calculator?

[sorrel]

so i have another test to do tomorrow and there is a no calculator part where you have to evaluate "simple" logs
for example







my biggest issues are with the ones that either have fractions or negative numbers as answers

is there a different way to solve them besides thinking "49 to the x power is 7"?

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[SeventhSandwich]

For first, if it's smaller than your base, obviously the logarithm has to be negative.

Then, just take your base and give it different exponents until it fits.

Also, what questions have you gotten that have fractions as answers?

[sorrel]

For first, if it's smaller than your base, obviously the logarithm has to be negative.

Then, just take your base and give it different exponents until it fits.

Also, what questions have you gotten that have fractions as answers?

the pics broke :c
anyway things like log (base 2) 1/2 is the fraction thing i meant

[TristanLuigi]

log₂(1/2) = log(2^-1) = -1
there really isn't much better way to do it but if you get something like:
log₄(32)
you can split multiples into separate logs, like:
= log₄(2*16) = log₄(2) + log₄(16) = 0.5 + 2 = 2.5


also just curious what math class are you in (Alg I, Alg II, College Alg, Precalc...?)

[Tokerovin]

Always remember to consider the quality of the bark and the consistency of the rings.

[TristanLuigi]

Always remember to consider the quality of the bark and the consistency of the rings.

[childofdarkness016]

log₂(1/2) = log(2^-1) = -1
there really isn't much better way to do it but if you get something like:
log₄(32)
you can split multiples into separate logs, like:
= log₄(2*16) = log₄(2) + log₄(16) = 0.5 + 2 = 2.5


also just curious what math class are you in (Alg I, Alg II, College Alg, Precalc...?)

this is an algebra II topic as far as i know since i just took my test on logs

also i would help but the images won't load

honestly the easiest way to evaluate them is to just change the form from log to exponential, or vice versa. There's not much you can do without a calculator and the change-of-base formula. My teacher is part of the anti-calculator school of thought too, but even she permitted calculators for that test.

[McJob]

Always remember to consider the quality of the bark and the consistency of the rings.

[sorrel]

log₂(1/2) = log(2^-1) = -1
there really isn't much better way to do it but if you get something like:
log₄(32)
you can split multiples into separate logs, like:
= log₄(2*16) = log₄(2) + log₄(16) = 0.5 + 2 = 2.5


also just curious what math class are you in (Alg I, Alg II, College Alg, Precalc...?)

Hmm that makes sense
This is for college algebra which its basically algebra 2.5

[ßlöükfáce]

log₂(1/2) = log(2^-1) = -1

this makes sense to me but

there really isn't much better way to do it but if you get something like:
log₄(32)
you can split multiples into separate logs, like:
= log₄(2*16) = log₄(2) + log₄(16) = 0.5 + 2 = 2.5

can you explain this to me? i'm not in algebra but i like to know stuff

[Headcrab Zombie]

I read 'evaluating' as 'evacuating' and was very confused as to how calculators were relevant

But yeah logs are one of those things I do well during math class then completely forget afterwards

[shamester]

Hi! I am currently learning LOGS and have a test tomorrow, I can help.


-- I meant to say rewrite them as multiplying when you are adding them





My school blocked imgur, so I can't see the pictures, I hope they are in the right order.

[TristanLuigi]

Hmm that makes sense
This is for college algebra which its basically algebra 2.5

oo i took that last semester
good luck

[shamester]

Do you need natural LOG to?

[sorrel]

I took the quiz I knew all of them except didn't know what to do with ln(e) and I put 10. But after googling it was 1
Darn

But thanks guys!