NTA Abhyas JEE Main2020MathematicsDifferentiationPractice
If f x = x - 4 x - 4 + t a n - 1 1 - 2 x 2 + x ,   ∀ 4 < x < 8 , then the value of f ′ 5 is equal to
Options
- A- 7 13
- B0
- C5 13
- D- 8 13
Correct answer
A. - 7 13
Step-by-step solution
f x = x - 4 2 + 2 2 - 2.2 x - 4 + t a n - 1 1 2 - x 1 + 1 2 . x f x = x - 4 - 2 2 + t a n - 1 1 2 - t a n - 1 x f x = 2 - x - 4 + t a n - 1 1 2 - t a n - 1 x ∵ x - 4 < 2 f ′ x = − 1 2 x − 4 − 1 1 + x 2 f ′ 5 = − 1 2 − 1 1 + 25 = − 14 26 = − 7 13