algebra question 2 - Gambling and Probability

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algebra question 2

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10-15-2016 , 12:10 PM

Kingkong352

journeyman

Join Date: Jul 2014 Posts: 382

Hi, if we have the equation X^5 = 0.7, what would be the operation to isolate the X ?

(I mean X*X*X*X*X = 0.7, I just don't find the symbol).

Thank you!

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10-15-2016 , 12:38 PM

whosnext

Carpal \'Tunnel

Join Date: Mar 2009 Posts: 6,731

You know about square roots?

For example, X^2 = 25 is solved by taking the square root of each side. So you would wind up with X = +/- Sqrt(25) = +/- 5.

Same thing for X^5 = 0.7.

You would need to take the "fifth root" of each side. Which is equivalent to taking each side to the (1/5) power.

Any calculator can do that.

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10-15-2016 , 12:59 PM

Kingkong352

journeyman

Join Date: Jul 2014 Posts: 382

Thanks, I know what is square root tough I did not think about it. But I don't understand how to take it to the 1/5 power ? I don't think we can just take the 0.7 and do square root 5 times or something, because for example 3*3*3 = 27, tough the square root of 27 is 5.1961...

I guess this is only an option on the calculator that I don't understand...

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10-15-2016 , 01:03 PM

whosnext

Carpal \'Tunnel

Join Date: Mar 2009 Posts: 6,731

Most calculators have a "y^x" key (the "^" symbol is implicit).

So to get 0.7^(1/5) you would enter 0.7 and then hit the "y^x" button. And then enter 0.2 since (1/5) = 0.2.

You should get a number around 0.931149915.

To check, you can then take that number to the 5th power and you'll get back to 0.7.

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10-15-2016 , 01:14 PM

Kingkong352

journeyman

Join Date: Jul 2014 Posts: 382

YESS !!! Thank you !!!!

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