Solve the Inequality: Understanding |5x-10| > 15

Absolute Value Inequalities with Two-Case Analysis

Given:

5x10>15 \left|5x-10\right|>15

Which of the following statements is necessarily true?

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1

Understand the problem

Given:

5x10>15 \left|5x-10\right|>15

Which of the following statements is necessarily true?

2

Step-by-step solution

To solve the inequality 5x10>15 \left|5x-10\right| > 15 , we rewrite it as two separate inequalities:

  • First inequality: 5x10>15 5x - 10 > 15
  • Second inequality: 5x10<15 5x - 10 < -15

Let's solve each one:

For the first inequality 5x10>15 5x - 10 > 15 :
Add 10 to both sides: 5x>255x > 25
Divide both sides by 5: x>5x > 5

For the second inequality 5x10<15 5x - 10 < -15 :
Add 10 to both sides: 5x<55x < -5
Divide both sides by 5: x<1x < -1

Combining these solutions, we have:
x>5x > 5 or x<1x < -1

Therefore, the correct statement regarding the solution set is: x>5 x > 5 or x<1 x < -1 .

3

Final Answer

x>5 x>5 or x<1 x<-1

Key Points to Remember

Essential concepts to master this topic
  • Rule: |expression| > number splits into two separate inequalities
  • Technique: Solve 5x - 10 > 15 AND 5x - 10 < -15
  • Check: Test x = 6: |5(6) - 10| = |20| = 20 > 15 ✓

Common Mistakes

Avoid these frequent errors
  • Treating absolute value inequality like an equation
    Don't solve 5x10>15 |5x - 10| > 15 as a single equation = only one solution! This misses half the answer. Always split into two cases: expression > positive number AND expression < negative number.

Practice Quiz

Test your knowledge with interactive questions

Given:

\( \left|2x-1\right|>-10 \)

Which of the following statements is necessarily true?

FAQ

Everything you need to know about this question

Why do I need two inequalities for one absolute value inequality?

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Because absolute value measures distance from zero! If 5x10>15 |5x - 10| > 15 , then 5x - 10 could be either greater than 15 OR less than -15. Both make the distance greater than 15.

How do I know when to use 'or' versus 'and'?

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For greater than (>), use OR because you want values far from zero on either side. For less than (<), you'd use AND because you want values close to zero.

What if I get confused about the direction of the inequality signs?

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Remember: expression>number |expression| > number means the expression is either very positive (> number) or very negative (< -number). Think of it as "far from zero."

How can I check if x = 0 works in my solution?

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Substitute: 5(0)10=10=10 |5(0) - 10| = |-10| = 10 . Since 10 is NOT greater than 15, x = 0 should NOT be in your solution set. This confirms x>5 x > 5 or x<1 x < -1 is correct!

Why is the answer 'or' instead of 'and'?

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Because a single x-value can't be both greater than 5 AND less than -1 at the same time! The solution includes values that satisfy either condition - that's why we use OR.

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