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Source: — Problem Solving |
Junior | Next Rank: 30 Posts
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by godspeed » Sat Nov 28, 2009 11:51 am
Need to use (a-b)^2 and then (a+b)*(a-b) ..I think the answer comes to around 10 - 2*20^(.5)
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Junior | Next Rank: 30 Posts
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by Gmatter2.0 » Mon Nov 30, 2009 8:06 pm
let x+y=5+Sqrt5
x-y=5-Sqrt5
(Sqrt(x+y)-Sqrt(x-y))2=x+y+x-y-2 Sqrt(x+y) Sqrt(x-y)
=5+Sqrt5+5-Sqrt5-2Sqrt((5+Sqrt5)(5-Sqrt5))
=10-2Sqrt(25-5)
=10-2Sqrt(20)
=10-4Sqrt(5)
Ans:
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