NTA Abhyas JEE Main2020MathematicsContinuity and DifferentiabilityPractice
If f x = e 2 x + 2 x + 1 - 1 2 x + 2 x + 1 : x ≠ 0 1 : x = 0 , then (where, . represents the greatest integer function)
Options
- Alim x → 0 + f x = 1
- Blim x → 0 - f x = e - 1
- Cf x is continuous at x = 0
- Df x is discontinuous at x = 0
Correct answer
D. f x is discontinuous at x = 0
Step-by-step solution
lim x → 0 + f x = lim h → 0 + f 0 + h = lim h → 0 + e 2 h + 2 h + 1 - 1 2 h + 2 h + 1 = lim h → 0 + e 2 h + 1 - 1 2 h + 1 = e - 1 And, lim x → 0 - f x = lim h → 0 + f 0 - h = lim h → 0 + e - 2 h - 2 h + 1 - 1 - 2 h - 2 h + 1 = lim h → 0 + e - 2 h - 1 - 2 h = 1 Since, lim x → 0 + f x ≠ lim x → 0 - f x , therefore, f x is not continuous at x = 0