Download Solving Equations with Decimals

Reteaching
Name
5-7
Solving Equations with
Decimals
To solve an equation, make the two sides of the equation equal with
the variable alone on one side. You can use inverse operations and
Properties of Equality.
Inverse operations are operations that “undo” each other. The Division
and Multiplication Properties of Equality say you can multiply or divide
both sides of an equation by the same number and the two sides remain
equal to each other.
Use division to “undo” multiplication.
Use multiplication to “undo” division.
With numbers: With numbers:
3.2 3 2.5 5 8
12.8 4 3.2 5 4
3.2 3 2.5 4 2.5 5 8 4 2.5
12.8 4 3.2 3 3.2 5 4 3 3.2
3.2 5 3.2
12.8 5 12.8
With variables:
With variables:
q 3 1.8 5 10.8
r 4 7.2 5 6
q 3 1.8 4 1.8 5 10.8 4 1.8
r 4 7.2 3 7.2 5 6 3 7.2
q 5 6
r 5 43.2
Evaluate each expression by using substitution.
1. 6n; n 5 2.3
2. 3x 2 8.1; x 5 6.4
3. r 1 53.3 4 r; r 5 6.5
For 4 through 6, evaluate each expression for x 5 3.1, x 5 6.2, and x 5 8.3.
4. 5x
5. 8.2 1 x 4 2
6. 2x 1 1.5x
7. Writing to Explain Explain how you would solve the equation 3.2x 5 38.4 by
describing the inverse operation and the property of equality needed.
R 5•7
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