NTA Abhyas 2020
- Exam
- NTA Abhyas
- Year
- 2020
- Subject
- Mathematics
- Chapter
- Continuity and Differentiability
NTA Abhyas 2020 · Mathematics · Continuity and Differentiability
Let f (x) = \ cases (1)/(x2) & : |x| ≥ 1 ^ 2 + β& : |x| < 1 cases...
Let \left(x\right) = \left\{.\right) is continuous and differentiable at any point, then
Options
- A
- B
- C
- D
Correct answer
B.
Step-by-step solution
The given function is clearly continuous at all points except possibly at
For to be continuous at we must have
… \left(1\right)f\left(x\right)x = 1,\lim_{x \to {1}^{-}}\dfrac{f\left(x\right) - f\left(1\right)}{x - 1} = \lim_{x \to {1}^{+}}\dfrac{f\left(x\right) - f\left(1\right)}{x - 1}⇒ \lim_{x \to {1}^{-}}\dfrac{\alpha{x}^{2} + \beta - 1}{x - 1} = \lim_{x \to {1}^{+}}\dfrac{\dfrac{1}{{x}^{2}} - 1}{x - 1}
Putting in \left(1\right),\beta = 2
For to be continuous at we must have
… \left(1\right)f\left(x\right)x = 1,\lim_{x \to {1}^{-}}\dfrac{f\left(x\right) - f\left(1\right)}{x - 1} = \lim_{x \to {1}^{+}}\dfrac{f\left(x\right) - f\left(1\right)}{x - 1}⇒ \lim_{x \to {1}^{-}}\dfrac{\alpha{x}^{2} + \beta - 1}{x - 1} = \lim_{x \to {1}^{+}}\dfrac{\dfrac{1}{{x}^{2}} - 1}{x - 1}
Putting in \left(1\right),\beta = 2