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Old 2005 March 27th, 06:55 PM   #11 (permalink)
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Re: the remainder ???

Quote:
Originally Posted by metodiev
I missed the first question:
so when n is divided by 7 the remainder is 5 so
n = 7k + 5
but we need 2n so we multiply by 2
2n = 14k + 10
factor out 7...
2n = 7(2k) + 10
==> the remainder when 2n is divided by 7 is 10
great job metodiev ! many thanks , i get now the idea from the remainde
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Old 2005 March 28th, 12:37 AM   #12 (permalink)
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Re: the remainder ???

Quote:
Originally Posted by metodiev
I missed the first question:
so when n is divided by 7 the remainder is 5 so
n = 7k + 5
but we need 2n so we multiply by 2
2n = 14k + 10
factor out 7...
2n = 7(2k) + 10
==> the remainder when 2n is divided by 7 is 10
So this is not the correct answer

-----------

n is div by 7 remainder is 5 , so

the equation for this is

n=7*x+5.

if u take x=1

n=12.

then 2n/7= 2*12/7= 24/7 , remainder is 3

------------


Also, for the picture question, I did it this way. Please correct me if i am wrong in my math logic.

the reminder when n is divided by 3 is 1 , and the reminder when n+1 is divided by 2 is 1 .

what is the reminder when n-1 is divided by 6

So, I did it like this.
n = 3k + 1
plug in k = 1

n = 3(1) + 1 => 4

n+1 = 2k + 1 => n = 2k = 2 since k = 1 (plug in)

So, the answer says its n-1, so i just go 4-1 = 3
and also by the 2nd equation, n = 2 when n + 1, so. n + 1 = 2 + 1 = 3. both agree... ok.. maybe this is wrong..


but for your math, why do you let k = 2j + 1. Thanks.
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Old 2005 March 28th, 12:53 AM   #13 (permalink)
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Re: the remainder ???

Thanks for pointing this out , I did this quickly and forgot to factor out 7
so we have n = 7k + 5
and 2n = 14k + 10 (of course the remainder cannot be 10 when 2n is divided by 7, the remainder can never be greater than or equal to the divisor - silly me!)
2n = 14k + 7 + 3
2n = 7(2k+1) + 3 ==> the remainder is 3

Quote:
but for your math, why do you let k = 2j + 1. Thanks.
OK, n = 2m ==> n is even number (m is integer)
n = 3k + 1
==> 3k + 1 must be even
==> 3k must be odd and only a product of odd*odd=odd
in general you represent odd numbers in the form of 2k+1 since you are sure it is odd for any integer
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Old 2005 March 28th, 01:20 AM   #14 (permalink)
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Re: the remainder ???

Quote:
Originally Posted by metodiev

OK, n = 2m ==> n is even number (m is integer)
n = 3k + 1
==> 3k + 1 must be even
==> 3k must be odd and only a product of odd*odd=odd
in general you represent odd numbers in the form of 2k+1 since you are sure it is odd for any integer
oh no no, Ididnt point it out, because I thought I got it wrong again.


2) Ahhh.. I now understand where you're coming from.. and how you get the remainder = 3.

Thanks again
_ _ _ _ SIG _ _ _ _
Please Correct my answers/POE method/reasonings in my post if you can.....

Thanks!

Also, Anyone in Philadelphia Region would like to get together and study or who with proven record is able to tutor me on weekends, Please PM me. Willing to pay for some tutoring.

GMAT Crushed me......


Now, I need help....
Why the hell I did not find this site before GMAT crushed me...........
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