Examine the following statements.
Remember that the base will be represented in (). Help these students.
Example 1
log (4) x = 12
log x = log 12
log 4
log x = 1.08 * 0.6
log x = 0.65
x = 4.5
Example 2
log (4) x = 12
log 4 = 12
x = 12 / log 4
x = 20
Example 3
log (4) x = 12
log (4) x = log 12
Example 4
log (4) x = 12
log (4)12 = x
Example 5
log (8) 32 = x
x = 8/32
x = 1/4
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ok the first exampl is wrong because you cant the 12 cus it will be in base 10
ReplyDeleteexample 2 is also wrong because you cant jus carry across the log4 either
ReplyDeletesomeone plz correct me but it think all are wrong
ReplyDeletelog (4) x = 12
ReplyDeleteI would say that you need to work out what can be found.
log 4 = 0.60
0.60 x = 12
x = 12 / 0.60
x=20
in example 1 above you cannot just remove the brackets. They are there for a purpose.
ReplyDeletein example 2 it is similar to the first step in example 1 so i would have to say it is not correct.
i think renjisan is correct they all seem to be wrong to me
ReplyDeleteEXAMPLE 1:
ReplyDeletelog (4)x= 12
So log (4)x=12 is in the form: log (b)a= c
Since log (b)a= c is equal to: b^c=a......
Therefore, log (4)x= 12......now becomes:
4^12= x
x = 16 777 216
Answer= 16 277216
Sry ppl, but i tink all u guys r wrong..........lol
nerd is not that we cant find the answer is jus that the way it is worked out here is wrong just read it that what we are commemting on say why it is wrong lol
ReplyDeletei totally agree with renjisan!! no one is trying to find the answer nerd, because its quite easy to find!!! we are just commenting on the errors. i actually think all are wrong!
ReplyDeleteAll are wrong because in e.g (1) you cannot just log the 12. in e.g (2) you cannot jus remove the x and afterwards place it back in. in e.g (3)you cannot jus log one side. in e.g (4) it would have been right if there wasn't a log in front of the 4. in e.g (5) well that was just crazyness!
ReplyDeletehey crazy kid can u explain d errors plz
ReplyDeleteOk, in example 1: log (4)x= 12:
ReplyDeleteWhen you got a problem like, log (4)x= 12, you simply, put the constant term/ term independent from the logarithm department to the POWER OF THE BASE, EQUAL TO THE TERM THAT IS BEING LOGGED, THATS IT!!!!!!!!!!!
i.e. log (b)a= c is EQUAL to: b^c= a
So, in example 1, log (4)x= 12 is simply equal to
4^12= x
So, x= 16 777 216.
in example 1 using log(a)b = logb/loga
ReplyDeleteso log(4)X = logX/ log4 = 12
then multiply both sides by log4
u then get logX = log4 * 12
the only error i example 1 is the log of 12
ReplyDeletethe same error is done in example 3
in example 5 the rule of log
log(a)b ~ logb / loga
to solve for X
so it should be log(8)32 = X ~ log32/log8 = X
i totally agree with renjisan, i think al;l the examples are wrong
ReplyDeleteespecially example 5;
Log(8) 32 = X
could simply be calculated as
Log (10) 32 / Log (10) 8
= 1.67.
Correct me if am wrong
well Darky, those brackets are there to indicate that it is a log
ReplyDeleteexample 2 can be change to exponent to solve for x
ReplyDeletei actually think reviewing the log rules miss gave us will help these problems significantly! because errors such as not putting a log into exponent form, is occuring
ReplyDeletewell that is tru because if some are correct as some ppl say that mean alot of us are making silly mistakes so we should go back to miss notes to double check
ReplyDelete2^3 = 8 ==> log(2) 8 = 3
ReplyDeleteWhenever with log problems like the examples 1-5, try to remember the statement above. It helps...
Hey guys i think all the examples are wrong also. I no its simple to work out, but what i cant understand is how the errors were made in the first place...
can someone explain...
log 4 x=12
ReplyDeletelogx/log4=12
x/4=log12
log12 x/4
log12x/4
x=log12/4
x=log12/log4
x=12/4
x=3
can someone tel me if ah wrong
ReplyDeleteassuming that it is log x to the base 4?
ReplyDeletewell up to ur second line is correct but after that its worng because u cant jus drop logs from the x and 4 and carry it across because its one term what u cud of done is something like this
logx/log4=12
carrying across log4 it becomes
logx=12Xlog4
den u can find out what 12Xlog4 is =7.225
then u find the anti log
soo u get x=log^-1X7.225
your final answer will be 16,777,216
OR
u can do it like this
log 4 x=12 rem that >>>> 2^3 = 8 ==> log(2) 8 = 3
so replace them and u get
4^12=x
and that = 16,777,216
well dark angel mis it intentionally so that we cud explain and show her that we no how to do it the correct way
ReplyDeleteeg2
ReplyDeletelog 4x=12
therefore logx/log4=12
carry across d log4
logx=12*log4
ans=7.225
x=log7.225
and from here ah dont understand what to do when ah do this my ans is .858
ah understan the second approach hoss ah rel weak in this ah relly need the help
All of them are wrong...and to work problems of dese kind..u will need to use the line approach of dividing the log x / log 4 = 12 ..work out wat can be worked and make x the subject of the formula..
ReplyDeleteExample 1
ReplyDeletelog (4) x = 12
log x = log 12
log 4
log x = 1.08 * 0.6
log x = 0.65
x = 4.5
This is wrong since you cannot just log 12
log (4) x = 12
this can be switched to exponent and x can be found, in which
log (4) x = 12
4^12 = x
Example 1
ReplyDeletelog (4) x = 12
log x/log 4 = log 12 L.H.S. IS ACCURATE , BRINGING IT TO A COMMON BASE WAS A WONDERFUL IDEA BUT U CANNOT JUST ADD LOG(10) TO THE 12 ON THE R.H.S..WHEN U DO THAT, U ARE CHANGING THE WHOLE SUM.THEREFORE THE REST OF THE SUM IS INCORRECT.
EXAMPLE 1 SHOULD OF BEEN DONE LIKE THIS:
ReplyDeleteLOG(4)x = 12
LOGx/LOG4 = 12
LOG x = 12 * LOG4
LOGx = 7.22
10^7.22 = x
x = 16.5 * 10^6
Example 2
ReplyDeletelog (4) x = 12
log 4 = 12
x = 12 / log 4
x = 20
4 is the base and it is impossible to take the base and multiply it just so. you supposed to change it to a common base (10) divide the logs with the same base, cross multiply and then solve.
THE ANSWER SUPPOSED TO BE THE SAME AS EXAMPLE 1.
CHECK THE SOLUTION.
Example 3
ReplyDeletelog (4) x = 12
log (4) x = log 12
YOU CANNOT JUST ADD A LOG JUST SO TO AN EQUATION. WHEN U DO THAT U ARE CHANGING THE WHOLE SUM. CHECK EXAMPLE 1 TO SEE AV APPROACH.
Example 4
ReplyDeletelog (4) x = 12
log (4)12 = x
you cannot just interchange the values because the whole sum is being changed and hence a different answer will be achieved.
Example 5
ReplyDeletelog (8) 32 = x
x = 8/32
x = 1/4
SO TNE LOG JUST DISAPPEARED. THINGS DON'T HAPPEN LIKE THAT.
THE CORRECT THING TO DO IS: DRAW LINE
=> LOG32/LOG8 = x
x = 1.667
well no.1 has the correct approach
ReplyDeletejust remember if tou dont see any base, bring to base 10