NTA Abhyas JEE Main2020MathematicsContinuity and DifferentiabilityPractice
Consider the function f x = x - 2 x 2 - 3 x + 2 , then the incorrect statement is
Options
- Af x is continuous at x = 1
- Bf x is continuous at x = 2
- Cf x is differentiable at x = 1
- Df x is differentiable at x = 2
Correct answer
C. f x is differentiable at x = 1
Step-by-step solution
∵   x - 2   &   x 2 - 3 x + 2 both are continuous ∀ x ∈ R ∴ f x is continuous ∀ x ∈ R Now, x 2 - 3 x + 2 = x - 1 x - 2 ∴   f x = x - 2 x - 1 x - 2 : x ∈ - ∞ , 1 ∪ 2 , ∞ - x - 2 x - 1 x - 2 : x ∈ 1,2 f x = x - 1 x - 2 2 : x ∈ - ∞ , 1 ∪ 2 , ∞ - x - 1 x - 2 2 : x ∈ 1,2 f ' x = x − 1 2 x − 2 + x − 2 2 :       x ∈ − ∞ , 1 ∪ 2 , ∞ W