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(165)^2 - (164)^2 =

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(165)^2 - (164)^2 = [#permalink]

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New post 10 Mar 2012, 23:53
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(165)^2 - (164)^2 =

A. 1
B. 100
C. 229
D. 329
E. 349
[Reveal] Spoiler: OA

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Re: Subtracting Squared Numbers [#permalink]

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New post 10 Mar 2012, 23:55
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CLearly :

a^2 - b^2 = (a+b) * (a-b)

=> (165)^2 - (164)^2 = (165 + 164) * (165 - 164) = 329 * 1

Answer - D
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Re: (165)^2 - (164)^2 = [#permalink]

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New post 11 Mar 2012, 00:07
Thanks!

... But what would you do if the problem were written more like this:

(165)^3 - (163)^3 =

or:

(165)^2 - (163)^3 =

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Re: (165)^2 - (164)^2 = [#permalink]

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New post 11 Mar 2012, 00:15
(165)^3 - (163)^3

You can use the formula a^3 - b^3

(165)^2 - (163)^3

Expand (163)^3 as (165 - 2)^3 to simplify further.
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Re: (165)^2 - (164)^2 = [#permalink]

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New post 11 Mar 2012, 00:24
I think I'll have to go to YouTube or something for the ^2 x ^3, but I think I get the ^3 x ^3:

(165)^2 - (164)^2 = (165)^3 - (164)^3 = 329

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Re: (165)^2 - (164)^2 = [#permalink]

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New post 16 Apr 2012, 07:10
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Stoneface wrote:
(165)^2 - (164)^2 =

A. 1
B. 100
C. 229
D. 329
E. 349


Difference between square of two consecutive numbers is = the sum of the of the two consecutive numbers

165+164 = 329

D
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Re: (165)^2 - (164)^2 = [#permalink]

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New post 27 Feb 2014, 21:32
Stoneface wrote:
(165)^2 - (164)^2 =

A. 1
B. 100
C. 229
D. 329
E. 349



Using the formula:

(a+1)^2 - a^2 = 2a+1

So, Answer = 164*2 + 1
= 328+1 = 329 = Answer = D
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Re: (165)^2 - (164)^2 = [#permalink]

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New post 28 Aug 2014, 16:37
Where can these rules for this particular problem be found?

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Re: (165)^2 - (164)^2 = [#permalink]

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New post 28 Aug 2014, 22:30
GMATcrusher wrote:
Where can these rules for this particular problem be found?


See Bunuel's signature for the Math exponents resources link.

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Re: (165)^2 - (164)^2 = [#permalink]

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New post 28 Aug 2014, 22:34
Stoneface wrote:
I think I'll have to go to YouTube or something for the ^2 x ^3, but I think I get the ^3 x ^3:

(165)^2 - (164)^2 = (165)^3 - (164)^3 = 329


No, the expansion is different for both, please see the exponents theory in the Math chapter resources section.

(165)^2 - (164)^2 = 329

(165)^3 - (164)^3 = 81181

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Re: (165)^2 - (164)^2 = [#permalink]

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GMATcrusher wrote:
Where can these rules for this particular problem be found?


Check Tips and hints on Algebra here: algebra-tips-and-hints-175003.html

Also, I suggest you to go through the following post ALL YOU NEED FOR QUANT and check links in my signature below.

Hope it helps.
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Re: (165)^2 - (164)^2 = [#permalink]

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Re: (165)^2 - (164)^2 = [#permalink]

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New post 22 Jan 2016, 10:42
I solved it slightly different:

165^2-(165-1)^2= 165^2-(165^2+1^2-2*165*1)= 165-165-1+330= 329

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Re: (165)^2 - (164)^2 =   [#permalink] 22 Jan 2016, 10:42
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