If the least common multiple of two prime numbers x and y is 10, where

Question

If the least common multiple of two prime numbers x and y is 10, where x > y, then the value of 2x + y is

A. 7
B. 9
C. 11
D. 12
E. 21

FacelessMan · Accepted Answer

LCM of two prime numbers will basically be multiple of those numbers. LCM = 10 = 2*5, both of which are prime.

Now we know x>y, so x=5 and y =2. 
2x+y = 2*5 + 2 = 10 + 2 = 12. Hence D.

Divyadisha · Answer

Since both are prime numbers there are only two factors for each 1 and the number itself.

LCM of two prime numbers = multiplication of the numbers

10= 2*5 or 5*2

But its given that x>y, hence x=5 and y =2

2x+y= 2*5 +2= 12

D is the answer

OptimusPrepJanielle · Answer

LCM (x,y) = 10 and both x an y are prime.
The only values of x and y can be 5 and 2 (x = 5 and y = 2)

2x + y = 2*5 + 2 = 12

Correct Option: D

stonecold · Answer

Excellent Question.
Here is what i did on this one ->
Since x,y are primes and x>y---->
LCM(x,y) => Product of x*y

Hence 10=xy
10=> 2*5

Thus x=5 ans y=2

So 2x+y=> 12

SMASH THAT D

BrentGMATPrepNow · Answer

2 and 5 are the only PRIME numbers with an LCM of 10
Since we're told x > y, we can conclude that x = 5 and y = 2

So, 2x + y = 2(5) + 2 = 12

Answer: D

Cheers,
Brent

BrushMyQuant · Answer

Theory: If two numbers are co-prime (have no common factor apart from 1) then their LCM = product of those numbers

If the least common multiple of two prime numbers x and y is 10
Simce x and y are prime so they will have only one common factor between them which is 1
=> x and y are co-prime numbers
So, LCM(x,y) = x*y = 10
So, x and y can be 2 and 5
But we know that x > y
=> x= 5 and y =2

2x + y = 2*5 + 2 = 12

So,  Answer will be D 
Hope it helps!

To learn more about LCM and GCD watch these videos

https://www.youtube.com/watch?v=7jPV6JD0908

https://www.youtube.com/watch?v=vtSsAjcF-0Y

bumpbot · Answer

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If the least common multiple of two prime numbers x and y is 10, where

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