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Math Help - divisor problem

  1. #1
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    divisor problem

    The least common multiple of two numbers is 105 and the greatest common divisor is 5. Which of the following could be the sum of the numbers?

    (A) 21 (B) 25 (C) 49 (D) 50 (E) 105
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  2. #2
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    Quote Originally Posted by sri340 View Post
    The least common multiple of two numbers is 105 and the greatest common divisor is 5. Which of the following could be the sum of the numbers?

    (A) 21 (B) 25 (C) 49 (D) 50 (E) 105
    least common multiple 105 the prime divisors of 105 , 3,5,7 so our two numbers is multiples of this three numbers just
    greatest common divisors 5 so say our numbers a,b
    5 is a divisors of a,b , 3,7 in one of them not both say "a" same for "7"
    so the cases for a,b

    a= 5*3 = 15
    b= 5*7 = 35
    a+b = 50

    a=5*3*7=105
    b=5 =5
    a+b = 110

    so D) is the answer
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