Addition, Subtraction, and Variables - Practice Problems

Background

Let's work some practice problems!

Question

Evaluate:

1. 5a + 3b + 6a - 2b 
2. 3 - 7c + 5x - 8 + 6y 

Answer

1. 5a + 3b + 6a - 2b = 7a + b
2. 3 - 7c + 5x - 8 + 6y = -5 - 7c + 5x + 6y

Analysis

When we're looking at adding and subtracting terms with variables, we combine "like terms". For instance, in Question 1, we combine the a terms and the b terms this way:

a + 3b + 6a - 2b

We can rewrite this as:

a + 6a + 3b - 2b

We can now add the terms more easily:

7a + b

Question 2

While there are a number of terms in this question, 3 - 7c + 5x - 8 + 6y, the only terms that can be worked with are the constants:

3 - 7c + 5x - 8 + 6y

3 - 8 - 7c + 5x + 6y

-5 - 7c + 5x + 6y

Vocabulary used:

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Where might you have come from?

Fact-orials Index

Operations with Different Kinds of Numbers:

• Addition, Subtraction, and Variables

Where might we go?

Operations with Different Kinds of Numbers:

• Multiplication, Division, and Variables