Which of the following is true for all real numbers and ?

Answer and explanation

Correct answer: B.

  1. Step 1: , so holds for all real , .
  2. Step 2: The others fail: becomes an equality when ; breaks for ; breaks for (); breaks for .
Answer
.
Why not the others: Each other inequality has a simple counterexample, whereas the first reduces to a square being non-negative.

Practise more Which statement is true?.

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