NTA Abhyas JEE Main2020MathematicsFunctionsPractice
The domain of the function f x = l o g 2 1 - l o g 12 x 2 - 5 x + 16 is
Options
- A1,4
- B- ∞ , 4
- C1 , ∞
- D1,4
Correct answer
A. 1,4
Step-by-step solution
The function f x is defined if 1 - l o g 12 x 2 - 5 x + 16 > 0 and x 2 - 5 x + 16 > 0 ⇒ l o g 12 x 2 - 5 x + 16 < 1 and x - 5 2 2 + 39 4 > 0 ⇒ x 2 - 5 x + 16 < 12 ∵ x - 5 2 2 + 39 4 > 0 ,   ∀ x ∈ R ⇒ x 2 - 5 x + 4 < 0 ⇒ x - 1 x - 4 < 0 ⇒ 1 < x < 4 ∴ Domain of f = 1,4