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If the least common multiple of two prime numbers x and y is 10, where
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02 Jul 2021, 10:20
02 Jul 2021, 10:20
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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
A. 7
B. 9
C. 11
D. 12
E. 21
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Re: If the least common multiple of two prime numbers x and y is 10, where
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02 Jul 2021, 10:30
02 Jul 2021, 10:30
1
Carcass wrote:
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
A. 7
B. 9
C. 11
D. 12
E. 21
The LCM of two prime numbers other than 2 is always an odd number
Here, LCM of x and y is 10
i.e. the numbers can be 2 and 5 only
Now, x > y
So, x = 5 and y = 2
Therefore, 2x + y = 2(5) + 2 = 10 + 2 = 12
Hence, option D
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If the least common multiple of two prime numbers x and y is 10, where
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02 Jul 2021, 20:24
02 Jul 2021, 20:24
1
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
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
