6th Grade Math Textbook, Fundamentals

Lesson 2-5 for exercise sets. &KDSWHU 

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Solve: 22 x 15

4 x 15 Simplify the power.

4  15 x 15  15

19 x

Check: 22 x 15

419  15

4  4 Tr u e

? Simplify the power and

substitute 19 for x.

Add 15 to both

sides to isolate x.

(^1) Solve:n 4  9  13
n 4  9  13 Combine like terms.
n 13  13 Simplify.
n 13  13  13  13
n 26
Check:n 4  9  13
26  4  9 13 Substitute 26 for n.
22  9 13 Simplify.
13  13 Tr u e
?
?
Add 13 to both
sides to isolate n.
2

Sometimes you need to simplify expressions before solving an equation.

Solve and check.

1. 7 x 12 2.g (14)  11 3. 11 y(4)^2 4.|8| f 13

5.Discuss and Write Are x(3) 9 and x6 equivalent equations?

Explain why or why not.

To solve an equation when the number being subtracted

is missing, write a related subtraction sentence.

Solve: 9 b 7 Check: 9 b 7

9  7 b Write a related sentence. 9  2 7 Substitute 2 for b.

2 b 7  7 Tr u e

You can use estimation and mental math to check

if the solution of an equation is reasonable.

Solve:x 21  117

First estimate by rounding: x 20  120 21 rounds down to 20, and 117 rounds up to 120.

140  20  120 Think: What number minus 20 is 120?

x 140

Then solve: x 21  117

x 21  21  117  21 Add 21 to both sides to isolate x.

x 138

?



Think

138 is close to the estimate of 140.

The answer is reasonable.