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Real Numbers
Question
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Find the LCM and HCF of the following integers by applying the prime factorisation method. (i) 12, 15 and 21 

Answer

(i) 12, 15 and 21 

Now,    12 = 2 × 2 × 3= 22 × 3,

15 = 3 × 5, 21 = 3 × 7

Here, 3 is the smallest common prime factor.

∴ H.C.F. (12, 15, 21) = 3

And 22, 31, 51 and 71 are the greatest powers of prime factors.

∴ L.C.M. (12, 15,21)= 22 × 31 × 51 × 71 =420.

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