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indices

work out the value of x when

2^30/8^9=2^x

how would i do this

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Replace 8 with 2^3.
Reply 2
Original post by little_wizard123
Replace 8 with 2^3.


ok so 2^30/2^3=2^x
(edited 11 years ago)
Reply 3
Original post by zed963
work out the value of x when

2^30/8^9=2^x

how would i do this


23089=2x \displaystyle \frac{2^{30}}{8^9} = 2^x

Remember, 8=23 8 = 2^3 , hence, 89 8^9 can be written as (23)9 (2^3)^9
Now use the law, (ax)b=axb (a^x)^b=a^{xb}
Original post by zed963
ok so 2^30/2^3=2^x


No. You have replaced 8^9 by 2^3.

8^9 = (2^3)^9. Then simplify this with an indices rule.
Reply 5
Original post by raheem94
23089=2x \displaystyle \frac{2^{30}}{8^9} = 2^x

Remember, 8=23 8 = 2^3 , hence, 89 8^9 can be written as (23)9 (2^3)^9
Now use the law, (ax)b=axb (a^x)^b=a^{xb}


so 2^30-2^27=2^3
Reply 6
Original post by zed963
so 2^30-2^27=2^3


Is the '-' a typo?
It should be a divisor.

Yes, we get 23 2^3 , but what is the value of x ? x \ ?
Reply 7
Original post by raheem94
Is the '-' a typo?
It should be a divisor.

Yes, we get 23 2^3 , but what is the value of x ? x \ ?


Yeah it's a typo

x=3
Reply 8
2^30 / 8^9 = 2^x
2^30 / (2^3)^9 = 2^x
2^30 / 2^27 = 2^x
2^3 = 2^x

x = 3
Reply 9
Original post by zed963
Yeah it's a typo

x=3


:yep:

You are getting better at maths!
Reply 10
Original post by kuroudo93
2^30 / 8^9 = 2^x
2^30 / (2^3)^9 = 2^x
2^30 / 2^27 = 2^x
2^3 = 2^x

x = 3


You may like to have a look at the forum rules, full solutions are considered a last resort.

So always first give hints, please don't post full solutions.
just expand 2^30 and divide it by 8^9 and you'll get 8. therefore x is 3
Reply 12
Original post by lmartynofficial
just expand 2^30 and divide it by 8^9 and you'll get 8. therefore x is 3


Can you please clarify what do you mean by expand 2^30?
Original post by lmartynofficial
just expand 2^30 and divide it by 8^9 and you'll get 8. therefore x is 3


You make it sound easy.
Original post by raheem94
Can you please clarify what do you mean by expand 2^30?


I think he literally means do 2*2*2*2.... 30 times and write the value without indices. And then the same with 8^9 :colonhash:
Reply 15
Original post by hassi94
I think he literally means do 2*2*2*2.... 30 times :colonhash:


My also guess was that he means this, but it doesn't looks sensible.

How will he divide by 8^9, any idea?
Original post by raheem94
My also guess was that he means this, but it doesn't looks sensible.

How will he divide by 8^9, any idea?


It is a pretty terrible solution to the problem.

Well you get 1073741824/134217728 and then he somehow sees that that = 8.

It's a silly solution, I wouldn't worry :tongue:
Reply 17
Original post by hassi94
It is a pretty terrible solution to the problem.

Well you get 1073741824/134217728 and then he somehow sees that that = 8.

It's a silly solution, I wouldn't worry :tongue:


That solution does actually work.
Reply 18
Original post by hassi94
It is a pretty terrible solution to the problem.

Well you get 1073741824/134217728 and then he somehow sees that that = 8.

It's a silly solution, I wouldn't worry :tongue:


At least he isn't trying to use the infinity concept someone used yesterday. lol

OP, please ignore post#12.
Reply 19
Original post by zed963
That solution does actually work.


We know it works, but how will you do it without a calculator?
You won't be able to see that the value is 8 without a calc.

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