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Help please!!!!!!!!!!!

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Help please!!!!!!!!!!!

by abuc0112 » Wed Sep 07, 2011 7:22 pm
If x is an integer and y = 3x + 2, which of the following CANNOT be a divisor of y ?
(A) 4
(B) 5
(C) 6
(D) 7
(E) 8
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by cans » Wed Sep 07, 2011 7:41 pm
IMO C
y=3x+2.
(3x+2)/6 will never be an integer. because 3x can be divisible by 6 when x is even. but 2 can't be divisible by 6.
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by pemdas » Wed Sep 07, 2011 9:12 pm
two answer choices are odd primes (5 and 7), hence divisibility of (3x+2) by these primes should allow for x to be odd integer

for the answer choice (4) if (3x+2) is divisible by 2 and greater than 2 then it must be divisible by 4

the same for answer choice (8) if (3x+2) is divisible by 4 and greater than 4 it must be divisible by 8

we are left with answer choice (6)
abuc0112 wrote:If x is an integer and y = 3x + 2, which of the following CANNOT be a divisor of y ?
(A) 4
(B) 5
(C) 6
(D) 7
(E) 8
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by edvhou812 » Thu Sep 08, 2011 1:16 am
You can also plug in numbers for x:

A: x=6 3x+2=20 (Out)
B: x=1 3x+2=5 (Out)
C: Hold. Can tell it will take a lot of plugging in...
D: x=11 3x+2=35 (Out)
E: x=2 3x+2=8 (Out)

If four are out, it must be the only one that remains. Answer: C
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by navami » Thu Sep 08, 2011 6:09 am
(3x+2)/6 is never integer
IF X IS EVEN :
3X is divisible by 6
but 3X+2 will give 2 as reminder


IF X is oDD:
3x = ODD
3X+ 2 = ODD
Hence can not be divisible by 6
This time no looking back!!!
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