Use multiples to find the LCD for each pair of fractions.

a) 1/2, 1/3

b) 1/4, 1/5

To find the least common denominator (LCD) for each pair of fractions, you need to find the least common multiple (LCM) of their denominators.

a) For 1/2 and 1/3:
First, list the multiples of 2: 2, 4, 6, 8, 10, 12, 14, ...
Then, list the multiples of 3: 3, 6, 9, 12, 15, ...
You can see that the smallest common multiple of 2 and 3 is 6. Therefore, the LCD for 1/2 and 1/3 is 6.

b) For 1/4 and 1/5:
Start by listing the multiples of 4: 4, 8, 12, 16, 20, ...
Next, list the multiples of 5: 5, 10, 15, 20, 25, ...
The smallest common multiple of 4 and 5 is 20. Thus, the LCD for 1/4 and 1/5 is 20.

In summary:

a) The LCD for 1/2 and 1/3 is 6.
b) The LCD for 1/4 and 1/5 is 20.

By finding the least common multiple (LCM) of the denominators, you can determine the least common denominator (LCD) for a pair of fractions.

a)

Multiples:
2, 4, 6, 8, 10
3, 6, 9, 12
Which is the LCD?

b)
Do the same for these denominators.

a) The lowest common denominator would be 6?

b) Would the lcd be 20?

Both answers are right.