NTA Abhyas JEE Main2020MathematicsDifferentiationPractice
If ϕ x = log 8 log 3 x , then ϕ ′ e is equal to
Options
- Ae log 8
- B– e log 8
- C1 e log 8
- DNone of these
Correct answer
C. 1 e log 8
Step-by-step solution
We have, ϕ x = log 8 log 3 x = log 8 log x log 3 = log 8 log x - log 8 log 3 = log log x log 8 - log 8 log 3 ϕ ′ x = 1 log 8 ⋅ 1 log x ⋅ 1 x − 0 ∴ ϕ ′ e = 1 log 8 ⋅ 1 log e ⋅ 1 e = 1 e log 8