Answer:
Step-by-step explanation:
To write fractions with a common denominator, you will most likely need to scale some numbers up! I will explain how.
Let's try it with the fractions
2
3
and
3
12
12 is larger than 3, so we will have to multiply the 3 by some number to equal 12. (We are really finding the Least Common Multiple of the two denominators!) To do this, you have to multiply the 3 by 4, because 3x4=12. But now the numerator doesn't match the denominator. When you scale the denominator up, you have to scale the numerator up too! So the 2 must be multiplied by 4 also.
Now you have the following:
8
12
and
3
12
These fractions now have common denominators! Now they're all set for adding or subtracting fractions.
Try another:
2
6
and
3
5
: The least common multiple of 6 and 5 is 30. (the product of the denominators)
Transform each fraction by multiplying by "1":
2
6
⋅
5
5
=
10
30
and
3
5
⋅
6
6
=
18
30
One last problem:
4
9
and
7
6
What is the least common multiple of 9 and 6? Could you use 54? Absolutely, but it is not the LEAST number that you could use. How about 18? YES!
4
9
⋅
2
2
=
8
18
and
7
6
⋅
3
3
=
21
18
Ready to go...
Hope this helped!
