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by user123321 » Fri Jan 13, 2012 6:33 am
sud21 wrote:Is 3x+1 divisible by 10?
1) x = 4n+2
2) x > 4


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1) as x = 4n+2, assuming n an integer
we have 3(4n+2) + 1 = 12n+7
this will not be divisble by 10 since 12n+7 will always be an odd integer. hence suff.

2)x>4
3x+1 can be or cannot be divisible 10. so insuff.

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by neelgandham » Fri Jan 13, 2012 7:21 am
My 2 cents.

Is 3x+1 divisible by 10? For 3x+1 to be divisible by 10 the units digit of x should be 3. i.e x should be an odd Integer.
1) x = 4n+2 = even. Sufficient to tell that 3x+1 is not divisible by 10,

p.s: Assumption: n is an Integer
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