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Math Expert V
Joined: 02 Sep 2009
Posts: 59711
What is the value of a - b ? (1) a^2 - b^2 = 9 (2) a^2 - 2ab + b^2 = 1  [#permalink]

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Difficulty:   55% (hard)

Question Stats: 51% (01:41) correct 49% (01:16) wrong based on 39 sessions

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What is the value of (a - b) ?

(1) $$a^2 - b^2=9$$

(2) $$a^2-2ab+b^2=1$$

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Math Expert V
Joined: 02 Aug 2009
Posts: 8309
Re: What is the value of a - b ? (1) a^2 - b^2 = 9 (2) a^2 - 2ab + b^2 = 1  [#permalink]

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What is the value of (a - b) ?

(1) $$a^2 - b^2=9$$
(a-b)(a+b)=9... a-b could be anything 1,9,1/9,-1,

(2) $$a^2-2ab+b^2=1.......(a-b)^2=1......a-b=1..or ..a-b=-1$$

Combined
a-b=1...a+b=9
a-b=-1..a+b=-9
Insufficient

E

Note a and b could be anything — positive or negative, integer or fraction
_________________ Re: What is the value of a - b ? (1) a^2 - b^2 = 9 (2) a^2 - 2ab + b^2 = 1   [#permalink] 13 Nov 2019, 02:10
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# What is the value of a - b ? (1) a^2 - b^2 = 9 (2) a^2 - 2ab + b^2 = 1  