6th Grade Math Textbook, Fundamentals

Lesson 2-4 for exercise sets. &KDSWHU 

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Solve and check.

1.x 9  21 2. 52 s 37 3. 12 y(2) 4.|7| w 1  11

Estimate each solution. Then find the actual solution of the equation.

5.m 67  77 6. 46 h 83 7. 85 k(4)^2 8. 4 z 7  0

9.Discuss and Write Compare and contrast the steps you would use

to solve x 5 12 and x(5) 12. Explain your answer.

Whether the variable in an addition equation is on the right or left side of the

equal sign, you use the Subtraction Property of Equality to solve the equation.

Solve:|6|  24 x

6  24  24  24 x Subtract 24 from both sides to isolate x.

 18 x

Check:|6|  24 x

|6 | 24 (18) Substitute 18 for x.

6  6 Tr u e

Sometimes you need to combine like numerical terms when solving an equation.

Solve: 12 d 5 (8)  41

d 12  5 (8) 41 Use the Commutative Property.

d 9  41 Combine like numerical terms.

d 9  9  41  9 Subtract 9 from both sides to isolate d.

d 32

Check: 12 d 5 (8)  41

12  32  5 (8) 41 Substitute 32 for d.

41  41 Tr u e

You can use estimation and mental math to check if a solution is reasonable.

Solve: 436 x 575

First estimate by rounding: 440x 580 436 rounds up to 440, and 575 rounds up to 580.

440  140  580 Think: 440 plus what number is 580?

x 140

Then solve: 436 x 575

436  436 x 575  436 Subtract 436 from both sides to isolate x.

x 139

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Remember:|6|  6

means “is approximately equal to”

Think

139 is close to the estimate of 140. The answer is reasonable.