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4/ (√20 - √12) =

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4/ (√20 - √12) =

by sanju09 » Fri Jun 18, 2010 4:49 am
4/ (√20 - √12) =
(A) 1
(B) ½
(C) 4/√8
(D) √5 - √3
(E) √5 + √3
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by kvcpk » Fri Jun 18, 2010 5:06 am
We arrive at 1/2(sqrt(20) + sqrt(12)) by multiplying and divinding with (sqrt(20) + sqrt(12)

= sqrt(5) + sqrt(3)

E
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by amising6 » Fri Jun 18, 2010 5:19 am
4/ (√20 - √12) =
(A) 1
(B) ½
(C) 4/√8
(D) √5 - √3
(E) √5 + √3

4/ (√20 - √12)
4/(2√5 -2√3)
dividing both numerator and denominator by 2 we get
2/(√5-√3)
now multiplying both numerator and denominator by (√5+√3)

(2*(√5+√3))/((√5+√3)*(√5-√3))

(2*(√5+√3))/(5-3)
(2*(√5+√3))/2
hence √5 + √3

answer E
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