Skip to main contentSkip to solution

Which of the following facts are not true ?( Where RR is set of real numbers)

A. ∣x+y∣≤∣x∣+∣y∣,x,y∈R|x+y| \le |x|+|y|, x,y \in R

B. ∣x−y∣≥∣x∣+∣y∣,x,y∈R|x-y| \ge |x|+|y|, x,y \in R

C. ∣x+y∣≥∣x∣+∣y∣,x,y∈R|x+y| \ge |x|+|y|, x,y \in R

D. ∣x−y∣≤∣x∣+∣y∣,x,y∈R|x-y| \le |x|+|y|, x,y \in R

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 3

The triangle inequality gives ∣x+y∣≤∣x∣+∣y∣|x+y| \le |x|+|y| and ∣x−y∣≤∣x∣+∣y∣|x-y| \le |x|+|y|, so A and D are true. B fails for x=y=1x=y=1, where 0≥20 \ge 2 is false, and C fails for x=1x=1, y=−1y=-1. So B and C are the untrue statements.

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question