Page 90 - Math Course 1 (Book 1)

Solving Equations

Mo. 2

Lesson 8 Solve by Using Division

Example
KEY CONCEPTS:
1. Solve equations containing rational Solve 9a = 3.6. Check your solution.
numbers.
9a = 3.6 Write the equation.

9a 3.6 Divide each side by 9.
=
9 9
MO. 2 - L8a Simplify. Check the
Solve Equations Containing Answer a = 0.4 solution

Rational Numbers Solve by Using Multiplication

Let’s Begin Example

-3

Solve t = -6 . Check your solution.
5
Solve by Using Addition and
Subtraction -3 t = -6 Write the equation.
5
Examples
(
-5 ( -3 t = -5 ( -6 ) Multiply each side by -5
3 5 3 3
Solve m + 8.6 = 11.2.
30 Simplify. Check
m + 8.6 = 11.2 Write the equation. Answer t= 3 or 10 the solution.
m + 8.6 – 8.6 = 11.2 – 8.6 Subtract 8.6 from
each side.
m = 2.6 Simplify. REAL WORLD EXAMPLE
CEREAL

Answer 2.6 5
Torrey eats cup of cereal each morning and
6
2
another cup as a snack after school. If one
3 3 3
Solve y - = Check your solution.
8 4 box of cereal contains 10 cups of cereal, how
many days will the box last?
3 3 Write the equation.
y- =
8 4 The amount of cereal that Torrey eats each
3
y- 3 + 3 = 3 + 3 Add to each side. day is 5 + 2 = 5 + 4 = 9 or 1 1 cups.
6
2
6
6
6
3
8 8 4 8 8
Words 1 1 cups times the number equals 10
6 3 Rename the fractions 2 cups per day of days of cereal.
y = +
8 8 using the LCD and add.
Variable Let d = the number of days
9 1
Answer y = or 1 Simplify
8 8 1
Equation 1 • d = 10
2
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