Find the LCD of each pair of expressions

Question

1) 5/n, 6/3h

 

2) 4/a^2b^3, 3/9ab^4

 

 

Answer 1

The LCD is the denominator that the fraction pairs have in common.  When we have the LCD, we are able to add and subtract them because the fractions are part of the same whole.  When this happens, we are able to accurately compare them.

 

1)

 

5/n , 6/(3h)

 

If we multiply 5/n by (3h / 3h)  and multiply 3/(3h) by (n / n), both fractions will have the denominator 3hn.  Therefore, the LCD is 3hn.

 

 

2)

 

4 / (a²b³) , 3 / (9ab⁴)

 

 

Multiply  4/(a²b⁴)  by  (9b/9b)  and  multiply  3/(9ab⁴)  by  (a/a).  The LCD is 9a²b⁴.