Adding Algebraic Fractions
(KS3, Year 8)
How to Add Algebraic Fractions
To add algebraic fractions, use the rule:
A Real Example of How to Add Algebraic Fractions
Question
Add the algebraic fractions below.
Step-by-Step:
1
Compare the fractions you are adding with the rule shown above.
By comparing, we see that a = x, b = 2, c = y, d = 3.
By comparing, we see that a = x, b = 2, c = y, d = 3.
2
Use the rule, with a = x, b = 2, c = y, d = 3:
3
Calculate the terms in the rule. Where we have written two numbers or letters in brackets together, multiply them together:
(x)(3) = x × 3 = 3x
(2)(y) = 2 × y = 2y
(2)(3) = 2 × 3 = 6
Answer:
We have added x⁄2 and y⁄3:
Understanding The Rule
The letters written next to each other denotes that they are multiplying each other.
The rule works when the a, b, c and d are numbers, letters, terms or expressions.
Make sure you can:
Why Does This Work?
When adding fractions (algebraic or not) all of the fractions must have a common denominator. If initially the denominators are not the same...
...multiplying the denominators together will make a common denominator.
But having multiplied the denominator of each fraction, the numerator must be multiplied by the same value if we are not to change the fraction.
This gives us the rule for adding algebraic fractions:
This page was written by Stephen Clarke.
Worksheet
This test is printable and sendable
