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# Number System- Divisibility

Author Message
Manager
Joined: 24 Jan 2010
Posts: 151

Kudos [?]: 75 [0], given: 14

Location: India
Schools: ISB

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26 Jun 2010, 01:18
If x is divisible by 42. Which of the following
numbers is definitely a factor of x2? (Choose
all that apply.)
a) 63 b) 33 c) 36 d) 8

It will be helpful if group can explain the answer as well.
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If you like my post, consider giving me a kudos. THANKS!

Kudos [?]: 75 [0], given: 14

Manager
Joined: 16 Apr 2010
Posts: 212

Kudos [?]: 147 [2], given: 12

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26 Jun 2010, 21:00
2
KUDOS
x is divisible by 42 means x = 42k where k is any natural number different from 0.
so x = 42k = 2*3*7k
x2 = x*x = 2*2*3*3*7*7*k*k

63 = 9*7 is factor of x2
33 = 3*11 is not a factor of x2
36 = 4*9 is a factor of x2
8 is not a factor of x2

Hope the above explanation is clear.

Kudos [?]: 147 [2], given: 12

Manager
Joined: 24 Jan 2010
Posts: 151

Kudos [?]: 75 [0], given: 14

Location: India
Schools: ISB

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27 Jun 2010, 04:15
jakolik wrote:
x is divisible by 42 means x = 42k where k is any natural number different from 0.
so x = 42k = 2*3*7k
x2 = x*x = 2*2*3*3*7*7*k*k

63 = 9*7 is factor of x2
33 = 3*11 is not a factor of x2
36 = 4*9 is a factor of x2
8 is not a factor of x2

Hope the above explanation is clear.

Thanks for the explanation Jakolik. +1 Kudos
_________________

_________________
If you like my post, consider giving me a kudos. THANKS!

Kudos [?]: 75 [0], given: 14

Re: Number System- Divisibility   [#permalink] 27 Jun 2010, 04:15
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# Number System- Divisibility

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