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Plus and Minus (Different Variables)


Different Variables

The only thing you have to remember here is that you don’t mix different variables. You don’t know what a and b are (the variables are substituted for an unknown number, so you don’t know which numbers the variables represent). You don’t know if a = b, or if ab. Therefore, a + b is just a + b.

Example 1

Calculate and simplify

3a + 2b 5a + 8a b

Here, there are two different variables, a and b. You have to calculate terms with a and b separately. Then you get

3a 5a + 8a + 2b b = 6a + b

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