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Core 1 maths AS question help? :(

http://i45.tinypic.com/2ywzacy.png

I drew the question on paint

the answer is n = 2/3? :/ how
Reply 1
Avatar for goldenkuri
goldenkuri
OP
sigh
Original post by goldenkuri
sigh


not sure if I'm doing it the right way..

But you do the cube root of 125/8 (i separated them) so its 5/2 then you square it so 25/4

I never really understood these well, but I'm retaking this exam so maybe I can understand it better, but I was taught to do it that way
(edited 11 years ago)
Reply 3
Avatar for goldenkuri
goldenkuri
OP
Original post by tinkerbell_xxx
not sure if I'm doing it the right way..

But you do the cube root of 125/8 (i separated them) so its 5/2 then you square it so 25/4


But if you cube root 125/8.. don't you have to cube root 25/4 too ?
Reply 4
Avatar for dslc
dslc
Original post by goldenkuri
http://i45.tinypic.com/2ywzacy.png

I drew the question on paint

the answer is n = 2/3? :/ how


You say 52 = 125?
Reply 5
Avatar for McLH
McLH
What exactly are you trying to work out? :/
Reply 6
Avatar for goldenkuri
goldenkuri
OP
Original post by dslc
You say 52 = 125?
God im confused
Reply 7
Avatar for goldenkuri
goldenkuri
OP
Original post by McLH
What exactly are you trying to work out? :/


The value of "n" :colondollar:
Original post by goldenkuri
But if you cube root 125/8.. don't you have to cube root 25/4 too ?


no because you want to find N, it's just there to show you what your final answer should equal :smile:
Reply 9
Avatar for dslc
dslc
Original post by goldenkuri
God im confused


No, sorry. I meant, in your working, you say 52 = 125.

Switch this to 53 and it should become a lot more obvious.
Reply 10
Avatar for McLH
McLH
Original post by goldenkuri
The value of "n" :colondollar:


Well yes,

So we have:

(1258)n=254 (\dfrac{125}{8})^n = \dfrac{25}{4} yes?

So, 5323=5222 \dfrac{5^3}{2^3} = \dfrac{5^2}{2^2}

So, you cube root the first fraction, what do you do to make it equal the second? Square.

Thus, n=23 n = \dfrac{2}{3}
Reply 11
Avatar for McLH
McLH
Original post by McLH
Well yes,

So we have:

(1258)n=254 (\dfrac{125}{8})^n = \dfrac{25}{4} yes?

So, 5323=5222 \dfrac{5^3}{2^3} = \dfrac{5^2}{2^2}

So, you cube root the first fraction, what do you do to make it equal the second? Square.

Thus, n=23 n = \dfrac{2}{3}


Law of indices being denominator = root, numerator = raised to
Reply 12
Avatar for davros
davros
16
Original post by McLH
Well yes,

So we have...


So, 5323=5222 \dfrac{5^3}{2^3} = \dfrac{5^2}{2^2}



Now you're confusing things - you've lost the power 'n' from your left hand side :smile:
Reply 13
Avatar for McLH
McLH
Original post by davros
Now you're confusing things - you've lost the power 'n' from your left hand side :smile:


I think the thread was already confused :colondollar:
Reply 14
Avatar for LusterMX
LusterMX
5^3/2^3 does not equal to 5^2/2^2

If this is a one marker, I think all you'd have to do is look at it knowing the laws of indices. 125 and 8 are familiar cubic numbers which should indicate which route you should take. Calculating powers should be C2 and beyond I think.
Reply 15
Avatar for davros
davros
16
Original post by LusterMX
Calculating powers should be C2 and beyond I think.


Has society really come down this far? This sort of thing used to be standard O Level material :smile: I'll get my coat :biggrin:
Reply 16
Avatar for McLH
McLH
Original post by LusterMX
5^3/2^3 does not equal to 5^2/2^2

If this is a one marker, I think all you'd have to do is look at it knowing the laws of indices. 125 and 8 are familiar cubic numbers which should indicate which route you should take. Calculating powers should be C2 and beyond I think.


Of course not, but showing where they are coming from helps the OP...
Original post by goldenkuri
http://i45.tinypic.com/2ywzacy.png

I drew the question on paint

the answer is n = 2/3? :/ how


Do you understand how to do it?
Reply 18
Avatar for Hasufel
Hasufel
16
you have: (52)3n=(52)2(\frac{5}{2})^{3n}=(\frac{5}{2})^{2}, so....
(edited 11 years ago)
Reply 19
Avatar for Hasufel
Hasufel
16
where you have the (5223)n(\frac{5^2}{2^3})^n on the left side, 5 should be to the power 3 - not 2, so you can then factor out the powers as i`ve done above.

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