M
Math Coach Amy
Amy Ferguson Moncure

SAT

Absolute Value

Find the solution when an absolute value equals 0. Use Guess and Check with the answer choices.

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What to Remember

Guess and Check

Use Guess and Check with the answer choices.

Substitute each value in the choice for x.

The choice works only when every value gives 0.

Example

|x − 7| = 0

x = −7, |−7 − 7| = |−14| = 14. No, continue.

x = 7, |7 − 7| = |0| = 0. Yes.

Together

Together

Work these three in a session. Use Guess and Check with the answer choices.

1

|x − 4| = 0

Which choice is the solution to the equation?

Use Guess and Check with the answer choices.

A. x = −4 B. x = 0 C. x = 4 D. x = −4 and x = 4
Show Answer

Use Guess and Check with the answer choices.

A. x = −4, |−4 − 4| = |−8| = 8. No, continue.

B. x = 0, |0 − 4| = |−4| = 4. No, continue.

C. x = 4, |4 − 4| = |0| = 0. Yes.

D. x = −4 and x = 4, |−4 − 4| = |−8| = 8 and |4 − 4| = |0| = 0. No.

Answer: C. x = 4

2

|x − 5| = 0

Which choice is the solution to the equation?

Use Guess and Check with the answer choices.

A. x = 5 B. x = −5 C. x = 0 D. x = −5 and x = 5
Show Answer

Use Guess and Check with the answer choices.

A. x = 5, |5 − 5| = |0| = 0. Yes.

B. x = −5, |−5 − 5| = |−10| = 10. No, continue.

C. x = 0, |0 − 5| = |−5| = 5. No, continue.

D. x = −5 and x = 5, |−5 − 5| = |−10| = 10 and |5 − 5| = |0| = 0. No.

Answer: A. x = 5

3

|x − 8| = 0

Which choice is the solution to the equation?

Use Guess and Check with the answer choices.

A. x = 0 B. x = −8 and x = 8 C. x = −8 D. x = 8
Show Answer

Use Guess and Check with the answer choices.

A. x = 0, |0 − 8| = |−8| = 8. No, continue.

B. x = −8 and x = 8, |−8 − 8| = |−16| = 16 and |8 − 8| = |0| = 0. No, continue.

C. x = −8, |−8 − 8| = |−16| = 16. No, continue.

D. x = 8, |8 − 8| = |0| = 0. Yes.

Answer: D. x = 8

Independent

Independent Practice

Try these five on your own. Use Guess and Check with the answer choices.

1

|x − 3| = 0

Which choice is the solution to the equation?

Use Guess and Check with the answer choices.

A. x = −3 and x = 3 B. x = 3 C. x = −3 D. x = 0
Show Answer

Use Guess and Check with the answer choices.

A. x = −3 and x = 3, |−3 − 3| = |−6| = 6 and |3 − 3| = |0| = 0. No, continue.

B. x = 3, |3 − 3| = |0| = 0. Yes.

C. x = −3, |−3 − 3| = |−6| = 6. No, continue.

D. x = 0, |0 − 3| = |−3| = 3. No.

Answer: B. x = 3

2

|x − 6| = 0

Which choice is the solution to the equation?

Use Guess and Check with the answer choices.

A. x = 0 B. x = −6 C. x = −6 and x = 6 D. x = 6
Show Answer

Use Guess and Check with the answer choices.

A. x = 0, |0 − 6| = |−6| = 6. No, continue.

B. x = −6, |−6 − 6| = |−12| = 12. No, continue.

C. x = −6 and x = 6, |−6 − 6| = |−12| = 12 and |6 − 6| = |0| = 0. No, continue.

D. x = 6, |6 − 6| = |0| = 0. Yes.

Answer: D. x = 6

3

|x − 9| = 0

Which choice is the solution to the equation?

Use Guess and Check with the answer choices.

A. x = 9 B. x = 0 C. x = −9 and x = 9 D. x = −9
Show Answer

Use Guess and Check with the answer choices.

A. x = 9, |9 − 9| = |0| = 0. Yes.

B. x = 0, |0 − 9| = |−9| = 9. No, continue.

C. x = −9 and x = 9, |−9 − 9| = |−18| = 18 and |9 − 9| = |0| = 0. No, continue.

D. x = −9, |−9 − 9| = |−18| = 18. No.

Answer: A. x = 9

4

|x − 2| = 0

Which choice is the solution to the equation?

Use Guess and Check with the answer choices.

A. x = −2 B. x = 2 C. x = 0 D. x = −2 and x = 2
Show Answer

Use Guess and Check with the answer choices.

A. x = −2, |−2 − 2| = |−4| = 4. No, continue.

B. x = 2, |2 − 2| = |0| = 0. Yes.

C. x = 0, |0 − 2| = |−2| = 2. No, continue.

D. x = −2 and x = 2, |−2 − 2| = |−4| = 4 and |2 − 2| = |0| = 0. No.

Answer: B. x = 2

5

|x − 11| = 0

Which choice is the solution to the equation?

Use Guess and Check with the answer choices.

A. x = −11 and x = 11 B. x = 0 C. x = 11 D. x = −11
Show Answer

Use Guess and Check with the answer choices.

A. x = −11 and x = 11, |−11 − 11| = |−22| = 22 and |11 − 11| = |0| = 0. No, continue.

B. x = 0, |0 − 11| = |−11| = 11. No, continue.

C. x = 11, |11 − 11| = |0| = 0. Yes.

D. x = −11, |−11 − 11| = |−22| = 22. No.

Answer: C. x = 11

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