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# 3^20 - 3^19

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Moderator
Joined: 18 Apr 2015
Posts: 5166
Followers: 77

Kudos [?]: 1033 [0], given: 4655

3^20 - 3^19 [#permalink]  12 Aug 2017, 09:54
Expert's post
00:00

Question Stats:

84% (01:46) correct 15% (00:59) wrong based on 19 sessions

 Quantity A Quantity B $$\frac{(3^{20} - 3^{19})}{3}$$ $$3^{18} + 3^{18}$$

A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
[Reveal] Spoiler: OA

_________________
GRE Instructor
Joined: 10 Apr 2015
Posts: 1238
Followers: 46

Kudos [?]: 1126 [1] , given: 7

Re: 3^20 - 3^19 [#permalink]  13 Aug 2017, 05:30
1
KUDOS
Expert's post
Carcass wrote:
 Quantity A Quantity B $$\frac{(3^{20} - 3^{19})}{3}$$ $$3^{18} + 3^{18}$$

A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.

Given:
Quantity A: (3^20 - 3^19)/3
Quantity B: 3^18 + 3^18

Factor Quantity A and combine the terms in Quantity B to get:
Quantity A: 3^19(3^1 - 1)/3
Quantity B: 2(3^18)

Simplify the numerator of Quantity A to get:
Quantity A: 3^19(2)/3
Quantity B: 2(3^18)

3^19 divided by 3 = 3^18. So, we get:
Simplify the numerator of Quantity A to get:
Quantity A: (3^18)(2)
Quantity B: 2(3^18)

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com

Re: 3^20 - 3^19   [#permalink] 13 Aug 2017, 05:30
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