IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => IGCSE/ GCSE => Math => Topic started by: **!!superexcited!!!** on October 27, 2009, 10:43:05 am

Title: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 10:43:05 am
Can any1 plz solve d question attatched......:
Title: Re: MATH HELP...!! URGENT...
Post by: Saladin on October 27, 2009, 10:54:12 am
n=5/3

u hav to use log, thats how i did it....

i cant explain...
Title: Re: MATH HELP...!! URGENT...
Post by: Deep on October 27, 2009, 11:06:21 am
32^(1/n) = 8
Using log,
(1/n)lg32 = lg8
(1/n) = lg8/lg32
n = 1/(lg8/lg32)
   = 5/3
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:06:56 am
n=5/3

u hav to use log, thats how i did it....

i cant explain...
hey the dude... Can u pleeeeeez type in the operation u use for log.... :)
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:07:21 am
Thanks... :)
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:08:55 am
 :)
32^(1/n) = 8
Using log,
(1/n)lg32 = lg8
(1/n) = lg8/lg32
n = 1/(lg8/lg32)
   = 5/3
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:11:50 am
Hey do u hv to use log for quests like   32 raised to n = 2
Title: Re: MATH HELP...!! URGENT...
Post by: Deep on October 27, 2009, 11:16:23 am
32 = 2^5

so 32^2 = 2^(5*2)
            = 2^10
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:17:53 am
 :)
32 = 2^5

so 32^2 = 2^(5*2)
            = 2^10
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:21:47 am
32 = 2^5

so 32^2 = 2^(5*2)
            = 2^10
Hey wait a min, I dint get that.. :(
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:23:34 am
this is d quest...
Title: Re: MATH HELP...!! URGENT...
Post by: astarmathsandphysics on October 27, 2009, 11:25:03 am
That is what i get.
Title: Re: MATH HELP...!! URGENT...
Post by: Ghost Of Highbury on October 27, 2009, 11:27:23 am
32 = 2^5

2^5n = 2

5n = 1

n = 1/5
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:29:07 am
32 = 2^5

2^5n = 2

5n = 1

n = 1/5
From wer do u get 5??   Can we use log for this question???
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:29:40 am
Cant see anythin... :(
That is what i get.
Title: Re: MATH HELP...!! URGENT...
Post by: nits94 on October 27, 2009, 11:30:06 am
see ...its like 2 to the power 5 is 32 right? so 32^n=2^5...so n=5...thats it...got it???
Title: Re: MATH HELP...!! URGENT...
Post by: Deep on October 27, 2009, 11:32:29 am
For the 1st 1..
U don't really ahve to use log.. I just realised that..
It's pretty simple in fact
32 = 2^5

 n Root of 32 = 32^(1/n)
Implying that 2^(5/n) = 8
Now, 8 = 2^3

=>    32^(1/n) = 2^(5/n) = 8 = 2^3

2^(5/n) = 8 = 2^3

=>>   Equating the powers of 2
        5/n = 3
        n = 5/3
This method is useful if you are not allowed the use of a calculator
Title: Re: MATH HELP...!! URGENT...
Post by: Ghost Of Highbury on October 27, 2009, 11:32:43 am
From wer do u get 5??   Can we use log for this question???

how will u express 4 as 2x

ofcourse it is 22 which is equal to 4

samething for 32

2what? = 32

2^5 = 32

yes u can use log this way

----
2x = 32

log232 = x

in ur calculator do this

(log 32)/ (log 2) to get the answer 5

follow the rest of the steps for solving

@nits94 - n is not equal to 5...u have to express 32 as 2^5 adn then do it
Title: Re: MATH HELP...!! URGENT...
Post by: sameer210394 on October 27, 2009, 11:33:16 am
From wer do u get 5??   Can we use log for this question???

this question does not expect log, though you can use...

32n = 2

in this case u have to rearrange 32n in such that its base is 2.

so 32 can be written as 25.

so now    
              25n  =   2

     now as the base are same, the power has to be the same, therefore 5n = 1

now solve for n and the answer is 0.2  or 1/5
Title: Re: MATH HELP...!! URGENT...
Post by: Ghost Of Highbury on October 27, 2009, 11:33:42 am
this is d quest...

the above was the answer for the quoted one..
Title: Re: MATH HELP...!! URGENT...
Post by: Deep on October 27, 2009, 11:34:23 am
For the 1st 1..
U don't really ahve to use log.. I just realised that..
It's pretty simple in fact
32 = 2^5

 n Root of 32 = 32^(1/n)
Implying that 2^(5/n) = 8
Now, 8 = 2^3

=>    32^(1/n) = 2^(5/n) = 8 = 2^3

2^(5/n) = 8 = 2^3

=>>   Equating the powers of 2
        5/n = 3
        n = 5/3
This method is useful if you are not allowed the use of a calculator
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:35:29 am
 :)Thanx
see ...its like 2 to the power 5 is 32 right? so 32^n=2^5...so n=5...thats it...got it???
Title: Re: MATH HELP...!! URGENT...
Post by: Ghost Of Highbury on October 27, 2009, 11:36:13 am
:)Thanx

thats a rong method..

n is not equal to 5

look at the method i sameer, deep and i gave above..
Title: Re: MATH HELP...!! URGENT...
Post by: nits94 on October 27, 2009, 11:37:20 am
m confused...i usually get it as n=5...n my teacher says its right...is it in any of the past papers???
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:37:36 am
 :) Thank u guys...Ur solutions really helped me...
Thanx again :)
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 11:38:31 am
yeah.. anywayz gtg study now... Talk to you later bye :)
m confused...i usually get it as n=5...n my teacher says its right...is it in any of the past papers???
Title: Re: MATH HELP...!! URGENT...
Post by: nits94 on October 27, 2009, 11:56:43 am
o ya ..u all r right...its llike
32^n=2
so 2^5n=2^1
that is 5n=1
n=1/5
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 02:34:13 pm
Hey guys sry to disturb ull but 1 more :) ....plz help
Title: Re: MATH HELP...!! URGENT...
Post by: Ghost Of Highbury on October 27, 2009, 02:36:02 pm
square both sides..

32 = 2^2p

5 = 2p

p = 2.5
Title: Re: MATH HELP...!! URGENT...
Post by: @d!_†oX!© on October 27, 2009, 02:37:41 pm
hey adi...shudn't it be like this???
root 32 = sp
=>21/5 = 2p
=>p = 1/5
Title: Re: MATH HELP...!! URGENT...
Post by: nid404 on October 27, 2009, 02:37:59 pm
root 32= 321/2


u know 25=32
so

so  25 ^1/2=2^p

so 2^5/2 = 2^p
p=5/2
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 02:39:20 pm
 :)Thanx i really get confused in these type of sums just wanted to confirm working...If possible can u do this one too...THANX a loooooot.... :)
square both sides..

32 = 2^2p

5 = 2p

p = 2.5
Title: Re: MATH HELP...!! URGENT...
Post by: **!!superexcited!!!** on October 27, 2009, 02:45:17 pm
 :) :)
root 32= 321/2


u know 25=32
so

so  25 ^1/2=2^p

so 2^5/2 = 2^p
p=5/2
Title: Re: MATH HELP...!! URGENT...
Post by: @d!_†oX!© on October 27, 2009, 02:48:47 pm
hey adi...shudn't it be like this???
root 32 = sp
=>21/5 = 2p
=>p = 1/5
oohhh sorry my fault...it shud be 25/2
just forgot it  in d hurry
Title: Re: MATH HELP...!! URGENT...
Post by: Alpha on October 31, 2009, 07:20:19 am
:)Thanx i really get confused in these type of sums just wanted to confirm working...If possible can u do this one too...THANX a loooooot.... :)


I have attached a file... See it.