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# exponential problem

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GRE Prep Club Legend
Joined: 07 Jun 2014
Posts: 4809
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
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Kudos [?]: 2083 [1] , given: 397

exponential problem [#permalink]  15 May 2018, 15:56
1
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Question Stats:

100% (00:19) correct 0% (00:00) wrong based on 12 sessions
$$(\sqrt{5}+\sqrt{7})^2=$$

A. 12
B. $$12 + 2\sqrt{3}$$
C. $$12 + 4\sqrt{3}$$
D. $$12 + \sqrt{35}$$
E. $$12 + 2\sqrt{35}$$
[Reveal] Spoiler: OA

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Sandy
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Kudos [?]: 2353 [1] , given: 33

Re: exponential problem [#permalink]  13 May 2019, 04:48
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Expert's post
sandy wrote:
$$(\sqrt{5}+\sqrt{7})^2=$$

A. 12
B. $$12 + 2\sqrt{3}$$
C. $$12 + 4\sqrt{3}$$
D. $$12 + \sqrt{35}$$
E. $$12 + 2\sqrt{35}$$

Use FOIL to expand the product

Note: $$(\sqrt{x})(\sqrt{y})=\sqrt{xy}$$

So, $$(\sqrt{5}+\sqrt{7})^2=(\sqrt{5}+\sqrt{7})(\sqrt{5}+\sqrt{7})$$

$$=\sqrt{25}+\sqrt{35}+\sqrt{35}+\sqrt{49}$$

$$=5+2\sqrt{35}+7$$

$$=12+2\sqrt{35}$$

Cheers,
Brent
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Brent Hanneson – Creator of greenlighttestprep.com

Re: exponential problem   [#permalink] 13 May 2019, 04:48
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