NTA Abhyas JEE Main2020MathematicsFunctionsPractice
f : R → R ,   f x = λ x + sin ⁡ x is onto if λ is an element of the set P and f x is one-one if λ is an element of the set Q , then (given, λ is a real number)
Options
- AP = Q
- BP ⊂ Q
- CP - Q = 0
- DQ ⊂ P
Correct answer
D. Q ⊂ P
Step-by-step solution
f ' x = λ + cos ⁡ x If f x is one-one, then λ ≥ - cos ⁡ x or λ ≤ - cos ⁡ x   ∀ x ∈ R ⇒ λ ∈ - ∞ , - 1 ∪ 1 , ∞ Further, f x has range R for λ ∈ R - 0 Hence, Q ⊂ P