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# (x-1)

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Founder
Joined: 18 Apr 2015
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(x-1) [#permalink]  14 May 2018, 12:22
Expert's post
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Question Stats:

94% (00:16) correct 5% (00:20) wrong based on 36 sessions
 Quantity A Quantity B $$(x-1)(x+1)$$ $$x^2$$

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

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Active Member
Joined: 07 Jan 2018
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Kudos [?]: 769 [1] , given: 88

Re: (x-1) [#permalink]  15 May 2018, 08:52
1
KUDOS
use foil to expand qty A
$$x^2 + x -x -1$$
or, $$x^2 - 1$$

subtract $$x^2$$ from both sides, we are left with
qty A =-1
qty B = 0

option B
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GRE Instructor
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Kudos [?]: 4470 [1] , given: 69

Re: (x-1) [#permalink]  13 May 2020, 08:30
1
KUDOS
Expert's post
We can solve this question using matching operations (my favorite Quantitative Comparison strategy)
Given:
Quantity A: $$(x-1)(x+1)$$
Quantity B: $$x^2$$

Use FOIL to expand and simplify the left side:
Quantity A: $$x^2 - 1$$
Quantity B: $$x^2$$

Subtract $$x^2$$ from both quantities to get:
Quantity A: $$-1$$
Quantity B: $$0$$

$$0 > -1$$, so the correct answer is B

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Re: (x-1)   [#permalink] 13 May 2020, 08:30
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