Solve the Absolute Value Equation: |2x + |x - 2|| = 1

Nested Absolute Value Equations with Case Analysis

2x+x2=1 |2x+|x-2||=1

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1

Understand the problem

2x+x2=1 |2x+|x-2||=1

2

Step-by-step solution

To solve the equation 2x+x2=1 |2x + |x - 2|| = 1 , we need to consider different cases based on the expression within the absolute value signs.

Case 1: x2 x \geq 2

  • Here, x2=x2 |x - 2| = x - 2 .
  • The equation becomes 2x+x2=1 |2x + x - 2| = 1 or 3x2=1 |3x - 2| = 1 .
  • This gives two sub-cases to solve:
    • Sub-case 1.1: 3x2=1 3x - 2 = 1 leads to 3x=3 3x = 3 , so x=1 x = 1 . However, x=1 x = 1 does not satisfy x2 x \geq 2 . Discard this solution.
    • Sub-case 1.2: 3x2=1 3x - 2 = -1 leads to 3x=1 3x = 1 , so x=13 x = \frac{1}{3} . But x=13 x = \frac{1}{3} does not satisfy x2 x \geq 2 . Discard this solution.

Case 2: x<2 x < 2

  • In this case, x2=2x |x - 2| = 2 - x .
  • The equation transforms into 2x+2x=1 |2x + 2 - x| = 1 , then simplifies to x+2=1 |x + 2| = 1 .
  • This leads to two sub-cases:
    • Sub-case 2.1: x+2=1 x + 2 = 1 leads to x=1 x = -1 . Since x=1<2 x = -1 < 2 , it is a valid solution.
    • Sub-case 2.2: x+2=1 x + 2 = -1 leads to x=3 x = -3 . Again, x=3<2 x = -3 < 2 holds, so this is also a valid solution.

Thus, the solutions to the equation are x=1 x = -1 and x=3 x = -3 .

Therefore, the correct answers are x=1 x = -1 and x=3 x = -3 .

3

Final Answer

x=1 x=-1 , x=3 x=-3

Key Points to Remember

Essential concepts to master this topic
  • Rule: Split nested absolute values by analyzing critical points first
  • Technique: For |x - 2|, split at x = 2 giving cases x ≥ 2 and x < 2
  • Check: Verify each solution satisfies its case condition and original equation ✓

Common Mistakes

Avoid these frequent errors
  • Ignoring case conditions when checking solutions
    Don't solve 3x2=1 3x - 2 = 1 to get x = 1 and accept it without checking x ≥ 2 = wrong answer! This violates the case assumption and leads to invalid solutions. Always verify each solution satisfies both the equation AND its case condition.

Practice Quiz

Test your knowledge with interactive questions

\( \left|x\right|=3 \)

FAQ

Everything you need to know about this question

Why do I need to split into cases for nested absolute values?

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Because the inner absolute value x2 |x - 2| changes its definition based on whether x is greater or less than 2. Each case gives you a different equation to solve!

How do I know which critical point to use for splitting cases?

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Look at the expression inside each absolute value. For x2 |x - 2| , the critical point is where x - 2 = 0, so x = 2 is your splitting point.

What if my solution doesn't satisfy the case condition?

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Discard it immediately! A solution is only valid if it satisfies both the simplified equation AND the original case condition (like x ≥ 2 or x < 2).

Can I have solutions from both cases?

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Absolutely! In this problem, both solutions x=1 x = -1 and x=3 x = -3 come from the same case (x < 2), but other problems might give solutions from different cases.

How do I verify my final answers?

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Substitute each solution back into the original equation 2x+x2=1 |2x + |x - 2|| = 1 . For x = -1: 2(1)+12=2+3=1 |2(-1) + |-1 - 2|| = |-2 + 3| = 1

Why can't I just remove all absolute value signs at once?

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Because absolute values have conditional definitions! You must carefully analyze when each expression is positive or negative before removing the absolute value signs.

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