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# For real numbers a and b, define a?b = (a^2 + b^2)^(1/2). What is the

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Math Expert
Joined: 02 Sep 2009
Posts: 54372
For real numbers a and b, define a?b = (a^2 + b^2)^(1/2). What is the  [#permalink]

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24 Mar 2019, 22:40
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Difficulty:

25% (medium)

Question Stats:

68% (01:10) correct 32% (01:19) wrong based on 22 sessions

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For numbers a and b, define $$a?b = \sqrt{a^2 + b^2}$$. What is the value of $$(5?12)?((-12)?(-5))$$?

(A) 0
(B) 17/2
(C) 13
(D) $$13\sqrt{2}$$
(E) 26

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Re: For real numbers a and b, define a?b = (a^2 + b^2)^(1/2). What is the  [#permalink]

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24 Mar 2019, 23:41
Bunuel wrote:
For numbers a and b, define $$a?b = \sqrt{a^2 + b^2}$$. What is the value of $$(5?12)?((-12)?(-5))$$?

(A) 0
(B) 17/2
(C) 13
(D) $$13\sqrt{2}$$
(E) 26

$$(5?12)?((-12)?(-5))$$
solve we get
13?13 = √13^2+13^2 = 13 √2
IMO D
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Re: For real numbers a and b, define a?b = (a^2 + b^2)^(1/2). What is the   [#permalink] 24 Mar 2019, 23:41
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# For real numbers a and b, define a?b = (a^2 + b^2)^(1/2). What is the

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