StreakPeaked· Practice

ExamsJEE MainMaths

DIRECTIONS: This question contains two statements: Statement-1 (Assertion) and Statement-2 (Reason). This question also has four alternative choices, only one of which is the correct answer. You have to select the correct choice. Let f(x)=(x+1)²−1, x≥−1 Statement-1: The set {x: f(x)=f⁻¹(x)}={0,−1}. Statement-2: f is a bijection.

  1. Statement-1 is true, Statement-2 is true. Statement-2 is not a correct explanation for Statement-1.
  2. Statement-1 is true, Statement-2 is false.
  3. Statement-1 is false, Statement-2 is true.
  4. Statement-1 is true, Statement-2 is true. Statement-2 is not a correct explanation for Statement-1.

Correct answer: Statement-1 is true, Statement-2 is true. Statement-2 is not a correct explanation for Statement-1.

Solution

f is increasing, so f(x)=f^-1(x) reduces to f(x)=x: (x+1)^2-1=x -> x^2+x=0 -> x=0,-1, so St-1 is true. f is also a bijection onto its range [-1,inf), so St-2 is true, but being a bijection does not by itself produce the specific solution set, so it is not the correct explanation.

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