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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
I don't know what to say, really. Three minutes to the biggest battle of our professional lives. You find out life's this game of inches, so is football. Because in either game - life or football - the margin for error is so small. I mean, one half a step too late or too early and you don't quite make it. One half second too slow, too fast and you don't quite catch it. I'll tell you this, in any fight it's the guy whose willing to die whose gonna win that inch. That's football guys, that's all it is. Now, what are you gonna do?
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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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