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If k is an integer

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by emalby » Sat Feb 26, 2011 4:26 am
I was also confused, however if you think about it, (35^2) - (1/k) will never result in an integer for k>1. In fact it will always be an integer, i.e. 35*35, minus a number smaller than 1, i.e. 1/k.

Therefore it cannot be an integer.
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by wayofjungle » Sat Apr 23, 2011 2:46 pm
These questions are dangerous if the correct answer isnt confirmed! I just wasted nearly 25 mins because the question was typed incorrectly, hopefully none of this bad logic will be remembered. I am unsubscribing from the daily BTGMAT questions right now, yikes!
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by sushantgupta » Tue May 03, 2011 9:18 pm
35^2 -1 = (36-1)^2 - = 36 (36 - 2) = 9 * 8 * 17 = 12 * 3 * 17
So the answer is D.
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by vexy999 » Wed Jun 29, 2011 1:26 am
The question confused me. I thought it was 35^2 -(1/k) when in fact I should have been thinking (35^2-1)/k..Do the questions appear like this on GMAT?
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by vexy999 » Wed Jun 29, 2011 1:33 am
11025-1=11024 is divisble by 8,16..not divisible by 9,12 and 17..so the question is (35^2-1)/k and not 35^2-1/k and hence the answer is D
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by vsathya » Sun Jul 03, 2011 7:27 pm
Answer: D

Easy way to square multiples of 5 is:

35^2 = (3*4)25 = 1225
45^2 = (4*5)25 = 2025
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by shingik » Fri Aug 19, 2011 10:49 am
The answer still appears to be D even with the original way it was posted. Because even if you set it up you will still have to rely on the prime factorization of 35^2 minus 1 to derive your answer.
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by saketk » Mon Aug 29, 2011 9:42 am
A good example of making a simple question look confusing. I request the poster to put brackets to avoid the confusion. BODMAS comes into play that way
I was confused for almost 30 seconds after looking at the expression.
Well the answer is D.
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by navami » Mon Aug 29, 2011 12:25 pm
@ Rahul thanks great explaination
This time no looking back!!!
Navami
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by olegpoi » Tue Aug 30, 2011 12:10 pm
D
1224/16 is not an integer
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by prateek_guy2004 » Tue Aug 30, 2011 12:18 pm
rockeyb wrote:Using the formula (x^2 - y^2 ) = (x+y)(x-y)

35^2 -1 = 35^2 - 1^2

We can write this as (35+1)(35-1)= 36 x 34

So the question becomes (36 x 34)/ k = int .

K is an integer .

so only number that can not divide completely is 8 .

[spoiler]Ans : A .[/spoiler]

whats the OA ?
Its a great approach and makes a ugly looking ques easy.....
Don't look for the incorrect things that you have done rather look for remedies....

https://www.beatthegmat.com/motivation-t90253.html
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by JS_2 » Tue Sep 06, 2011 10:42 pm
Ans: D
As the only option where 35^-1 is not divisible by k is 16. hence 35^2-1/16 is not an integer.
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by edvhou812 » Tue Sep 06, 2011 11:24 pm
35^2 = 1225. 1225-1 = 1224. Factors of 1224 are: 17,2,2,2,3,3.

A: 8=2^3
B: 9=2^2
C: 12=(2^2)*3
D: NONE OF OUR FACTORS MAKE 16
E: 17=17

Answer: D
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by Deependra1 » Sun Sep 11, 2011 6:45 am
Answer: D
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by prashant misra » Sun Sep 11, 2011 11:44 pm
i think the actual question is posted wrong as there are no braces given in the question which received .the question should be as follows(35^2-1)/k or something else
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