Page 40 - Math Course 1 (Book 2)

Linear Equations: Addition and Subtraction

Mo. 8

Lesson 2 Subtraction Property of Equality

Words If an equation is true and the same
number is subtracted from each side,
KEY CONCEPTS: the resulting equation is true.
1. Solve equations by using addition.
2. Solve equations by using subtraction. Symbols For any numbers a, b, and c, if a = b,
3. Solve equations by using addition or then a – c = b – c.
subtraction

Examples 17 = 17 3 = 3
MO. 8 - L2a 17 – 9 = 17 – 9 3 – 8 = 3 – 8
8 = 8 –5 = –5
Solving Equations:

Addition and Subtraction

Let’s Begin
Vocabulary A-Z

Let us learn some vocabulary
Solve by Adding

equivalent expressions Examples
If the same number is added to each side of an
equation, then the result is an equivalent equation. A. Solve h – 12 = –27. Then check your solution.
The solution of this equation
t + 3 = 5 h – 12 = –27 Original equation
is 2
Using the Addition Property of
t + 3 + 4 = 5 + 4 h – 12 + 12 = –27 + 12 Add 12 to each side.
Equality, add 4 to each side.
The solution of this equation is h = –15 –12 + 12 = 0
t + 7 = 9 Answer and –27 + 12 = –15
also 2.

solve an equation To check that –15 is the solution, substitute –15 for
To solve an equation means to f nd all values of h in the original equation.
the variable that make the equation a true
statement. B. Solve k + 63 = 92. Then check your solution.

x – 11 = 0 k + 63 = 92 Original equation
x – 11 + 11 = 0 + 11
x = 11 k + 63 + (–63) = 92 + (–63) Add 63 to each side.

k = 29 63+ (–63) = 0
Answer
Key Concept and 92 + (–63) = 29
To check that 29 is the solution, substitute 29 for k
in the original equation.
Addition Property of Equality

If an equation is true and the same number is added to each side, the resulting equation is
Words
true
Symbols For any numbers a, b, and c, if a = b, then a + c = b + c.
7 = 7 14 = 14
Examples 7 + 3 = 7 + 3 14 + (–16) = 14 + (–16)
10 = 10 8 = 8

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