Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
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Exercise 1 Page 173

Use the Addition Property of Equality to eliminate the subtraction.

p=- 1

Practice makes perfect
To solve the equation, we have to isolate p on one side. Using the Addition Property of Equality, we will add 3 to both sides of the equation. This will eliminate the subtraction. Let's do it!
p-3=-4
p-3+3=- 4+3
p=- 1
To check that this solution is correct, let's substitute p=- 1 into the original equation and simplify.
p-3=-4
- 1-3? =-4
- 4=- 4 âś“
Since the left-hand side and right-hand side are equal, p=- 1 is the correct solution.

Extra

Properties of Equality

There are four main Properties of Equality that we use when solving linear equations.

Properties of Equality
Addition Property of Equality If a=b, then a+c=b+c.
Subtraction Property of Equality If a=b, then a-c=b-c.
Multiplication Property of Equality If a=b, then ac=bc.
Division Property of Equality If a=b and c is not 0, then a/c=b/c.

In later chapters, you will learn about some more advanced Properties of Equality. As an example, there is a property for when we need to eliminate a radical or an exponent.

Power Property of Equality

If a=b, then a^m=b^m.