If the operation @ is defined by x@y=(xy)^1/2 for all

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If the operation @ is defined by x@y=(xy)^1/2 for all [#permalink]

17 Dec 2012, 07:43

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92% (01:35) correct

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If the operation @ is defined by x@y=\sqrt{xy} for all positive numbers x and y, then (5@45)@60 =

(A) 30
(B) 60
(C) 90
(D) 30\sqrt{15}
(E) 60\sqrt{15}

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Re: If the operation @ is defined by x@y=(xy)^1/2 for all [#permalink]

17 Dec 2012, 07:46

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Walkabout wrote:

If the operation @ is defined by x@y=\sqrt{xy} for all positive numbers x and y, then (5@45)@60 =

(A) 30
(B) 60
(C) 90
(D) 30\sqrt{15}
(E) 60\sqrt{15}

(5@45)@60 =(\sqrt{5*45})@60=(\sqrt{225})@60=15@60=\sqrt{15*60}=30.

Answer: A.
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Re: If the operation @ is defined by x@y=(xy)^1/2 for all [#permalink]

17 Dec 2012, 07:50

I'm writing the answer but Bunuel is too fast to reply, a machine

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Re: If the operation @ is defined by x@y=(xy)^1/2 for all [#permalink] 17 Dec 2012, 07:50

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If the operation @ is defined by x@y=(xy)^1/2 for all

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If the operation @ is defined by x@y=(xy)^1/2 for all

If the operation @ is defined by x@y=(xy)^1/2 for all

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