- Exam
- JEE Main
- Year
- 2021
- Date
- 25 July
- Shift
- Evening Shift
- Subject
- Mathematics
- Chapter
- Continuity and Differentiability
JEE Main 2021 · 25 July · Evening Shift · Mathematics · Continuity and Differentiability
If f(x) = \ cases ∫ _ 0 ^ x (5 + |1 - t|)dt, & x > 2 5x + 1, & x ≤...
Options
- A\left(x\right)x = 2
- Bf is everywhere differentiable
- C\left(x\right)x = 2
- D\left(x\right)x = 1
Correct answer
C. \left(x\right)x = 2
Step-by-step solution
We have, f\left(x\right) = \left\{\begin{cases}{∫}_{0}^{x}\left(5 + \left|1 - t\right|\right)dt, & x > 2 \\ 5x + 1, & x \le 2\end{cases}\right)</p><p>Therefore,f\left(x\right) = {∫}_{0}^{1}\left(5 + \left(1 - t\right)\right)dt + {∫}_{1}^{x}\left(5 + \left(t - 1\right)\right)dt= 6 - \dfrac{1}{2} + \left(4t + \dfrac{{t}^{2}}{2}\right){|}_{1}^{x}= \dfrac{11}{2} + 4x + \dfrac{{x}^{2}}{2} - 4 - \dfrac{1}{2}= \dfrac{{x}^{2}}{2} + 4x + 1f\left({2}^{+}\right) = 2 + 8 + 1 = 11f\left(2\right) = f\left({2}^{-}\right) = 5 \times 2 + 1 = 11f\left({2}^{+}\right) = f\left({2}^{-}\right)f\left(x\right)x = 2f is differentiable at
Now, and
Therefore, is not differentiable at