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If x + y = 4 and x - y = 2, then x2 - y2 =
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09 Dec 2021, 01:33
09 Dec 2021, 01:33
Expert Reply
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Question Stats:
92% (00:10) correct
7% (00:48) wrong based on 14 sessions
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If x + y = 4 and x - y = 2, then x² - y² =
(A) 4
(B) 8
(C) 12
(D) 16
(E) 64
(A) 4
(B) 8
(C) 12
(D) 16
(E) 64
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Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
If x + y = 4 and x - y = 2, then x2 - y2 =
[#permalink]
09 Dec 2021, 06:10
09 Dec 2021, 06:10
1
Carcass wrote:
If x + y = 4 and x - y = 2, then x² - y² =
(A) 4
(B) 8
(C) 12
(D) 16
(E) 64
(A) 4
(B) 8
(C) 12
(D) 16
(E) 64
Key concept: x² - y² is a difference of squares that can be factored as follows: x² - y² = (x + y)(x - y)
Substitute values to get: x² - y² = (4)(2) = 8
Answer: B
gmatclubot
If x + y = 4 and x - y = 2, then x2 - y2 = [#permalink]
09 Dec 2021, 06:10
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