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TMUA 2022 · Paper 2 · Question 14 of 20

TMUA 2022 Paper 2 Question 14

Inequalities and reasoning — Modulus inequalities as distances. Try it first; the answer and a full worked solution are below.

TMUA 2022 · Paper 2Inequalities and reasoningModulus inequalities as distances7 options
Consider the two inequalities: |x+ 5|<|x+ 11| |x+ 11|<|x+ 1| Which one of the following is correct?
  1. AThere is no real number for which both inequalities are true.
  2. BThere is exactly one real number for which both inequalities are true.
  3. CThe real numbers for which both inequalities are true form an interval of length 1.
  4. DThe real numbers for which both inequalities are true form an interval of length 2.
  5. EThe real numbers for which both inequalities are true form an interval of length 3.
  6. FThe real numbers for which both inequalities are true form an interval of length 4.
  7. GThe real numbers for which both inequalities are true form an interval of length 5.
Show the answer and worked solution
answer · D
  1. AThere is no real number for which both inequalities are true.
  2. BThere is exactly one real number for which both inequalities are true.
  3. CThe real numbers for which both inequalities are true form an interval of length 1.
  4. DThe real numbers for which both inequalities are true form an interval of length 2.
  5. EThe real numbers for which both inequalities are true form an interval of length 3.
  6. FThe real numbers for which both inequalities are true form an interval of length 4.
  7. GThe real numbers for which both inequalities are true form an interval of length 5.
Read each as a comparison of distances. The first says x is closer to 5 than to 11, which puts it beyond their midpoint: x>8. The second says x is closer to 11 than to 1, so x<6. Together they give 8 <x<6, an interval of length 2.