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# GMAT Prep Radicals and Exponents operations question

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Manager
Joined: 06 Jan 2008
Posts: 215

Kudos [?]: 132 [0], given: 1

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04 Oct 2009, 13:48
00:00

Difficulty:

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Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 1 sessions

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Can't figure out hwo to get this one to show up using html tags...

so i'll try it with text:

Kudos [?]: 132 [0], given: 1

Manager
Joined: 11 Sep 2009
Posts: 129

Kudos [?]: 421 [1], given: 6

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04 Oct 2009, 14:42
1
KUDOS

$$(\sqrt{9+\sqrt{80}} + \sqrt{9-\sqrt{80}})^2$$

$$= (\sqrt{9+\sqrt{80}} + \sqrt{9-\sqrt{80}})(\sqrt{9+\sqrt{80}} + \sqrt{9-\sqrt{80}})$$

$$= (9+\sqrt{80}) + 2\sqrt{9+\sqrt{80}}\sqrt{9-\sqrt{80}} + (9-\sqrt{80})$$

$$= 18 + 2\sqrt{9^2-\sqrt{80}^2}$$

$$= 18 + 2\sqrt{1}$$

$$= 20$$

Kudos [?]: 421 [1], given: 6

Founder
Joined: 04 Dec 2002
Posts: 15578

Kudos [?]: 28494 [0], given: 5112

Location: United States (WA)
GMAT 1: 750 Q49 V42

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07 Oct 2009, 21:45
Here is the code of the Math Tags:

Code:

[m](\sqrt{9+\sqrt{80}} + \sqrt{9-\sqrt{80}})^2[/m]

[m]= (\sqrt{9+\sqrt{80}} + \sqrt{9-\sqrt{80}})(\sqrt{9+\sqrt{80}} + \sqrt{9-\sqrt{80}})[/m]

[m]= (9+\sqrt{80}) + 2\sqrt{9+\sqrt{80}}\sqrt{9-\sqrt{80}} + (9-\sqrt{80})[/m]

[m]= 18 + 2\sqrt{9^2-\sqrt{80}^2}[/m]

[m]= 18 + 2\sqrt{1}[/m]

[m]= 20[/m]

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Kudos [?]: 28494 [0], given: 5112

Manager
Joined: 18 Jul 2009
Posts: 167

Kudos [?]: 115 [0], given: 37

Location: India
Schools: South Asian B-schools

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07 Oct 2009, 22:43
Agree with AKProdigy87....20 it is
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Bhushan S.
If you like my post....Consider it for Kudos

Kudos [?]: 115 [0], given: 37

Re: GMAT Prep Radicals and Exponents operations question   [#permalink] 07 Oct 2009, 22:43
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