Question

common denominator for 3/5,4/9 and 2/7.

Answer 1

Given fractions are 3/5,4/9, and 2/7.

List the multiples of denominators.

Multiples of 5 are 5,10,15,20,25,30,....,315,320...

Multiples of 9 are 9,18,27,36,45,54,63,...,315,324...

Multiples of 7 are 7,14,21,28,....,315,322,..

Least common denominator of given fractions is 315.

Generally when we find Least common denominator,

If the any denominator number of them is not multiple of other denominator, then you just multiply the denominator numbers.

7*9*5 = 315

 

Answer 2

Write the prime factorization of each denominator.

5 = 1 * 5 = 5¹

9 = 3 * 5 = 3² * 5¹

7 = 1 * 7 = 7¹

Multiply highest power of each factor in the either number.

L.C.D = 3² * 5¹ * 7¹ 

           = 315