What procedure is necessary for addition and subtraction of fractions?

Answer 1

First, you must make sure that the denominators are the same, so if you are adding 3/6 + 4/8, you have to make the denominators the same, but how?

to make the denominators the same, you have to find the LCM, which is the least common multiple, and in this case, 24 is the LCM, and so your fraction will look like this; 3*4/6*4 + 4*3/8*3, so now you have to multiply, and the answer will be 12/24 + 12/24, but remember DON'T ADD THE DENOMINATORS!!, so your answer will be 24/24 which can also be written as 1.

You need to ensure the denominators are the same, and this involves finding the LCM (the lowest common multiples). Once you have done this you add or subtract the numerators

eg

4/7 + 2/3

The LCM of 7 and 3 is 21, so you need to change the equation to read

12/21 + 14/21 = (12+14)/21 = 26/21 = 1 and 5/21.

Answer 2

1. Find a common denominator.2. Convert both fractions to that denominator.

3. Add or subtract the numerators.

So, for example:

To add 1/3 and 2/5,

1. The least common denominator is 15 (3 * 5) ( it doesn't have to be the least, but there's no reason to use a larger denominator)

2. 1/3 = 5/15 and 2/5 = 6/15

3. 5 + 6 = 11, so the answer is 11/15

For something more complex:

(2x - 3) / y - x / (2y + 1)

1. The least common denominator is 2y^2 + y

2a. (2x - 3) / y = (2x - 3) * (2y + 1) / (2y^2 + y)

2b. x / (2y + 1) = xy / (2y^2 + y)

3. (2x - 3) * (2y + 1) / (2y^2 + y) - xy / (2y^2 + y) = ((2x - 3) * (2y + 1) - xy) / (2y^2 + y)

3 (simplified) = (4xy - 6y + 2x - 3 - xy) / (2y^2 + y)

3 (simplified again) = (3xy - 6y + 2x - 3) / (2y^2 + y)