Question 108004
5 sqrt 2 - sq rt 5 (numerator)
5 sqrt 2 + sq rt 5 (denominator)
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Multiply numerator and denominator by (5sqrt2 - sqrt5) to get:

Numerator: [5sqrt2 - sqrt5]^2 
Denominator: (25*2)-5 

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Numerator: 25*2 +5 - 10sqrt(10)
Denominator: 45
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Numerator: 55 - 10sqrt(10)
Denominator: 45

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Reduce to get:

 = [11-2sqrt(10)]/9

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Cheers,
Stan H.