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# (20^2 - 18^2) - (19^2 - 17^2)?

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Manager
Joined: 20 May 2014
Posts: 234
Followers: 7

Kudos [?]: 30 [0], given: 163

(20^2 - 18^2) - (19^2 - 17^2)? [#permalink]  12 Nov 2017, 00:31
00:00

Difficulty:

5% (low)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
(20^2 - 18^2) - (19^2 - 17^2)?

A. 4
B. 36
C. 38
D. 76
E. 224

Kudos for correct solution.
[Reveal] Spoiler: OA
Director
Joined: 03 Sep 2017
Posts: 522
Followers: 0

Kudos [?]: 195 [0], given: 66

Re: (20^2 - 18^2) - (19^2 - 17^2)? [#permalink]  12 Nov 2017, 23:56
Using the formula for the difference of squares, we can rewrite the expression as (20-18)(20+18) - (19-17)(19+17) = 2(20+18) - 2(19+17) = 2[(20+18)-(19+17)] = 2*2 = 4.

Re: (20^2 - 18^2) - (19^2 - 17^2)?   [#permalink] 12 Nov 2017, 23:56
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