Problems....

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shaheen12342's picture
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The sum of 20 distinct numbers is 801. What is their minimum LCM possible?
Choose one answer.
a. 360
b. 480
c. 42
d. 840

What is the remainder when (17)^36 + (19)^36 is divided by 111?

secondharsa's picture
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111 = 3 x 37

111 = 3 x 37

Euler Function of 37 is 36 [ 37 x ( 1- 1/37) ]

So both the numbers gives reminder 1 when divided by 1

1736 = 1 mod (36)

1936 = 1 mod (36)

Agaian reminder of 1736  divided by 3

=reminder of ( 18 - 1) 36  divided by 3

=reminder of ( - 1) 36  divided by 3

=1

Similarly for 1936 

reminder of 1936  divided by 3

= reminder of (18+1)36  divided by 3

= 1

Thus the answer = 1. 1 + 1. 1 = 2

 

shaheen12342's picture
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i see a flaw...

hi there...
thx a lot for ur solution but i think it's going wrong at the last step...don't u think we hv to apply chinese theorem at the last??

regards,
shaheen

Incognito (not verified)
Incognito's picture
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Yes we would have required

Yes we would have required to find out the values of such numbers for which the reminder is 1 if the reminder was not 1 for any of the numbers

But as here all the reminders are 1 there is no need to do anything else.

any how what else you want to prove using CRT

rajorshi's picture
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1

1

anita1's picture
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rajorshi are suggesting the

rajorshi are suggesting the answer is 1 ?

anyhow nice to see you back

busy in onsite or what

rajorshi's picture
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no! i posted a wrong

no! i posted a wrong solution but i could not erase it . the editor wont let me. hence the 1 . sorry for the confusion.

anyways i have a serious doubt which i dont have time to verify !!

i thought xn + yn  is divisible by (x+y) but it doesnot seem that way. can some one tell me what is the flaw. 

Anyways ,THIS time i am a hell lot busy and i am gonna return only 5 days before CAT . what a mess.

secondharsa's picture
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 xn + an is exactly

 xn + an is exactly divisible by (x + a) if n is odd, but not if n is even

For quick reference you can check other similar conditions @

http://www.cat4mba.com/math-e-book/number-system

atul duggal's picture
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1?

guys how the remainder is 1 can u explain

secondharsa's picture
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Use the calculator .The

Use the calculator .

The answer is 2.

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