• Best of luck to the class of 2024 for their HSC exams. You got this!
    Let us know your thoughts on the HSC exams here
  • YOU can help the next generation of students in the community!
    Share your trial papers and notes on our Notes & Resources page
MedVision ad

Logs! (1 Viewer)

skankit

Member
Joined
Jan 25, 2004
Messages
158
argh, does anyone else really hate logs?
for some reason, i never seem to get the answers right...! i dont get it..!!
grrrrr
:chainsaw:
 

KeypadSDM

B4nn3d
Joined
Apr 9, 2003
Messages
2,631
Location
Sydney, Inner West
Gender
Male
HSC
2003
I love 'em

If you're finding them troublesome, just learn the rules off by heart, and they'll be simple.

Log_a[b^c] = c * Log_a
Log_a = Log_c/Log_c[a]
Log_a + Log_a[c] = Log_a[bc]
Log_a - Log_a[c] = Log_a[b/c]

Now these ones are just extras which are useful to know:

Log_a * Log_b[a] = 1
a^(1/Log_b[a]) = b

And I forgot the most important one, the very definition of a log.

a = b^(Log_b[a])
 
Last edited:

Giant Lobster

Active Member
Joined
Jul 3, 2003
Messages
1,322
Location
asdads
Gender
Male
HSC
2004
Originally posted by ...
wtf r u doing here!!!!!!!!
LOL! what a way to greet someone :D
just cos shes an english mod doesnt mean she's not allowed to help ppl with logs. :p
 

Grey Council

Legend
Joined
Oct 14, 2003
Messages
1,426
Gender
Male
HSC
2004
Hokay, just clearing this up a bit, and adding a few more rules.

Basics first:
log<sub>b</sub>MN = log<sub>M</sub> + log<sub>b</sub>N
log<sub>b</sub>M/N = log<sub>M</sub> - log<sub>b</sub>N
log<sub>b</sub>b = 1
log<sub>b</sub>1 = 0
log<sub>b</sub>b<sup>k</sup> = k


What Keypad posted, but tidied up a bit (easier to read):
Log<sub>a</sub>b<sup>c</sup> = c * Log<sub>a</sub>b
Log<sub>a</sub>b = Log<sub>c</sub>b / Log<sub>c</sub>a
Log<sub>a</sub>b * Log<sub>b</sub>a = 1
a<sup>1/Log_b[a]</sup> = b
a = b<sup>Log_b[a]</sup>

YAY to the QUICKEDIT feature. :D
and if i made a mistake, please let me know.

Learn all those by heart, you'll have a lot less difficulty. And no, learn off by heart doesn't mean rote learn all of them. Try to understand em. As in think about it for a bit, 'understand' it, and you won't forget it. Logs laws aren't all that hard to learn. Unlike trig rules. :-\
 
Last edited:

Grey Council

Legend
Joined
Oct 14, 2003
Messages
1,426
Gender
Male
HSC
2004
you like em? Easy to read, and i don't mind if you print it and give it to your students. :p

but we should have this stickied somewhere. So many people ask for this. I myself didn't know any of them till the yearlies for year 11.
 

victorling

Member
Joined
Jan 10, 2004
Messages
465
Location
underground, Tokyo
Gender
Undisclosed
HSC
N/A
Originally posted by Grey Council
you like em? Easy to read, and i don't mind if you print it and give it to your students. :p

but we should have this stickied somewhere. So many people ask for this. I myself didn't know any of them till the yearlies for year 11.
i haven't got much students yet(3 at this moment)..lol
:) :) :)
 

Grey Council

Legend
Joined
Oct 14, 2003
Messages
1,426
Gender
Male
HSC
2004
ah well. They'll get more when the word spreads around.

Thing is, we can't tell if your a good TEACHER. I mean, sure, you can be good at maths, but teaching is a talent. It doesn't really come with knowledge. :( You can have a person getting a UAI of 70, but if he inspires his STUDENTS to work, he is a successful teacher. Cause its the student working that will help the student. If the student doesn't work, tuition won't help.
and don't take that wrong. I'm just observing.
 

victorling

Member
Joined
Jan 10, 2004
Messages
465
Location
underground, Tokyo
Gender
Undisclosed
HSC
N/A
Originally posted by Grey Council
ah well. They'll get more when the word spreads around.

Thing is, we can't tell if your a good TEACHER. I mean, sure, you can be good at maths, but teaching is a talent. It doesn't really come with knowledge. :( You can have a person getting a UAI of 70, but if he inspires his STUDENTS to work, he is a successful teacher. Cause its the student working that will help the student. If the student doesn't work, tuition won't help.
and don't take that wrong. I'm just observing.

u r very correct
thats really the truth
 

KeypadSDM

B4nn3d
Joined
Apr 9, 2003
Messages
2,631
Location
Sydney, Inner West
Gender
Male
HSC
2003
log<sub>b</sub>MN = log<sub>b</sub>M + log<sub>b</sub>N
log<sub>b</sub>M/N = log<sub>b</sub>M - log<sub>b</sub>N
log<sub>b</sub>b = 1
log<sub>b</sub>1 = 0
log<sub>b</sub>b<sup>k</sup> = k


What Keypad posted, but tidied up a bit (easier to read):
Log<sub>a</sub>b<sup>c</sup> = c * Log<sub>a</sub>b
Log<sub>a</sub>b = Log<sub>c</sub>b / Log<sub>c</sub>a
Log<sub>a</sub>b * Log<sub>b</sub>a = 1
a<sup>1/Log_b[a]</sup> = b
a = b<sup>Log_b[a]</sup>

Now they're right.
 

Grey Council

Legend
Joined
Oct 14, 2003
Messages
1,426
Gender
Male
HSC
2004
whoops, a few typos by me. lol, shouldn't have just copied pasted to save time. :$ hehe
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top