JEE Main 202325 JanuaryMorning Shift
- Exam
- JEE Main
- Year
- 2023
- Date
- 25 January
- Shift
- Morning Shift
- Subject
- Mathematics
- Chapter
- Functions
JEE Main 2023 · 25 January · Morning Shift · Mathematics · Functions
Let f: (0, 1) → ℝ be a function defined by f(x) = 1 1 - e ^ - x ,...
Let be a function defined by , and . Consider two statements
(I) is an increasing function in \left(0, 1\right)g
Then,
Options
- AOnly (I) is true
- BOnly (II) is true
- CNeither (I) nor (II) is true
- DBoth (I) and (II) are true
Correct answer
D. Both (I) and (II) are true
Step-by-step solution
Given,
f\left(x\right) = \dfrac{1}{1 - {e}^{- x}}g\left(x\right) = \left(f\left(- x\right) - f\left(x\right)\right)g\left(x\right) = f\left(- x\right) - f\left(x\right)g ( x ) = \dfrac{1}{1 - {e}^{x}} - \dfrac{{e}^{x}}{{e}^{x} - 1}⇒ g\left(x\right) = \dfrac{1 + {e}^{x}}{1 - {e}^{x}}x⇒ {g}^{'}\left(x\right) = \dfrac{2{e}^{x}}{{\left(1 - {e}^{x}\right)}^{2}} > 0
Since is always positive
So, is one-one in \left(0, 1\right)g\left(x\right)