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**XaiDiv****Member**- From: Antarctica
- Registered: 2021-08-22
- Posts: 25

hey guys, how can I calculate the value of

√(1-a) / √(1+a) - √(1+a) / √(1-a) ?

(a = 1 / √5 fyi.)

Hellooooooooooooo

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**Bob****Administrator**- Registered: 2010-06-20
- Posts: 9,425

hi XaiDiv

If you collect the two fractions over a common denominator you'll get:

square this and divide by a squared to get

Then substitute the given value and you're there.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Sometimes I deliberately make mistakes, just to test you! …………….Bob

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**XaiDiv****Member**- From: Antarctica
- Registered: 2021-08-22
- Posts: 25

Thank you bob!!! this might sound a bit weird but could you write out the solution step-by-step all the way to the end? I'm having a bit of trouble understanding why the numerator is -2a.

Hellooooooooooooo

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**Bob****Administrator**- Registered: 2010-06-20
- Posts: 9,425

so

If a = 1/root(5) then

There are two values for k; +1 and -1. We need to investigate which fits the original expression.

so

So the value k = -1 is the one we want.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Sometimes I deliberately make mistakes, just to test you! …………….Bob

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**XaiDiv****Member**- From: Antarctica
- Registered: 2021-08-22
- Posts: 25

tysm bob <3

Hellooooooooooooo

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