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# What is the value of a - b ? (1) a^2 - 2ab + b^2 = 16 (2) |a - b| = 4

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Math Expert
Joined: 02 Sep 2009
Posts: 51101
What is the value of a - b ? (1) a^2 - 2ab + b^2 = 16 (2) |a - b| = 4  [#permalink]

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12 Dec 2017, 04:55
00:00

Difficulty:

25% (medium)

Question Stats:

73% (00:52) correct 27% (01:10) wrong based on 107 sessions

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What is the value of a - b ?

(1) a^2 - 2ab + b^2 = 16
(2) |a - b| = 4

_________________
Math Expert
Joined: 02 Aug 2009
Posts: 7101
Re: What is the value of a - b ? (1) a^2 - 2ab + b^2 = 16 (2) |a - b| = 4  [#permalink]

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12 Dec 2017, 05:27
Bunuel wrote:
What is the value of a - b ?

(1) a^2 - 2ab + b^2 = 16
(2) |a - b| = 4

1) $$a^2-2ab+b^2=16......(a-b)^2=16$$
So a-b can be 4 or -4
Insufficient

2) |a-b|=4
This tells us that the distance between a and b is 4, but value could be 4 or-4
Insufficient

Combined..
Both values 4 and -4 still possible..
Insufficient

E
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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Re: What is the value of a - b ? (1) a^2 - 2ab + b^2 = 16 (2) |a - b| = 4 &nbs [#permalink] 12 Dec 2017, 05:27
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