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Author Topic: A Math Question  (Read 2664 times)

PTTG??

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A Math Question
« on: April 24, 2009, 09:17:35 pm »

2^x=n, solve for x, where n is a power of ten.
Is there more than one answer?

I don't know myself.
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Heron TSG

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Re: A Math Question
« Reply #1 on: April 24, 2009, 10:01:24 pm »

There are infinite powers of ten. Therefore, there are infinite answers.
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Re: A Math Question
« Reply #2 on: April 24, 2009, 10:05:53 pm »

There are infinite powers of ten. Therefore, there are infinite answers.

Potentially; but can you prove that there is at least one x where x^2 results in a number that is one followed by any number of zeros and only zeros? Perhaps it would be better to ask what the lowest value of x is.
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SolarShado

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Re: A Math Question
« Reply #3 on: April 24, 2009, 10:32:45 pm »

Note: your equation could be better written as "2^x=10^y" and then what values of x will result in y being an integer (whole number)"

however, i'm not sure there is any solution. all powers of 2, when reduced to a list of prime factors will look like {2 2 2 ... 2}, but a power of ten, reduced to the same form will have pairs of {5 2}.

in other words, all powers of 10 will be divisible by 2 and 5, but powers of 2 will only be divisible by 2.

I could be wrong, do you have a number that does fit your requirements? Because
Is there more than one answer?
makes it sound like you do.
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G-Flex

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Re: A Math Question
« Reply #4 on: April 24, 2009, 10:37:12 pm »

2^x=n, solve for x, where n is a power of ten.
Is there more than one answer?

I don't know myself.

Is x is some PARTICULAR power of 10, there's only one answer.

If n isn't defined though, and you're just asking if there's more than one solution set for 2^x=n, then yeah, of course there's more than one, since the value of x will change depending on what n is.
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Re: A Math Question
« Reply #5 on: April 24, 2009, 10:42:14 pm »

Note: your equation could be better written as "2^x=10^y" and then what values of x will result in y being an integer (whole number)"

however, i'm not sure there is any solution. all powers of 2, when reduced to a list of prime factors will look like {2 2 2 ... 2}, but a power of ten, reduced to the same form will have pairs of {5 2}.

in other words, all powers of 10 will be divisible by 2 and 5, but powers of 2 will only be divisible by 2.

I could be wrong, do you have a number that does fit your requirements? Because
Is there more than one answer?
makes it sound like you do.

What about zero?
2^0=10^0

Heron TSG

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Re: A Math Question
« Reply #6 on: April 24, 2009, 10:43:06 pm »

X could be infinitely close to zero. (I think.)
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Re: A Math Question
« Reply #7 on: April 24, 2009, 10:44:22 pm »

But then it wouldn't be an integer.

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Re: A Math Question
« Reply #8 on: April 24, 2009, 10:49:16 pm »

The original post didn't say integer...
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Re: A Math Question
« Reply #9 on: April 24, 2009, 11:48:02 pm »

Just to clarify; I don't even know if there is one. I'm kind of leaning to no, with what solarshado said.

My original thought was if there was a power of 2 that was 1 followed by any number of zeros, but I like the way this is going.
« Last Edit: April 25, 2009, 12:05:17 am by PTTG?? »
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SolarShado

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Re: A Math Question
« Reply #10 on: April 25, 2009, 12:01:19 am »

"what about zero?" he says. *facepalm* there's that...  ::) ;) good one TME.

Good point Barbarossa, about the integer thing. I assumed we'd be using positive integers, cuz IME ther're the most commonly used.

I suspect you could find fractional values for x and y to make both sides equal to within a very small amount. If it weren't so late i'd be tempted to try and find such values ;D I'm a nerd that way.
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Ampersand

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Re: A Math Question
« Reply #11 on: April 25, 2009, 12:16:17 am »

There are infinitely many solutions assuming that the values for x and y can be fractional values. If you require an integer solution, there is only Zero.

-0.5382 is one such fractional solution
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Re: A Math Question
« Reply #12 on: April 25, 2009, 12:22:41 am »

if X can be negative, you can go down to .000000(times infinite)1
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Strife26

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Re: A Math Question
« Reply #13 on: April 25, 2009, 01:19:24 am »

This reminds of the fun I had messing with my new TI-89 Titanium today.

Did you know that calculators don't like it when you tell them to take quadnomials to powers of over a hundred. I like to play with equations like this. I just lack a calculator right now.
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Re: A Math Question
« Reply #14 on: April 25, 2009, 02:44:49 am »

2^x = 10^y

log_10(2^x) = log_10(10^y)

log_10(2^x) = y

Alternatively,

x = log_2(10^y)

Plug in any value of x you like, and you will get a value for y. Or plug in integer values of y, and get the value of x that will generate them. x will probably be irrational, but it will exist for every y you try.
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