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JEE Main 20241 FebruaryMorning Shift
Exam
JEE Main
Year
2024
Date
1 February
Shift
Morning Shift
Subject
Mathematics
Chapter
Functions

JEE Main 2024 · 1 February · Morning Shift · Mathematics · Functions

Let f: R → R and g: R → R be defined as f(x) = \ cases _ e x, & x >...

Let f:R→Rf: R \to R and g:R→Rg: R \to R be defined as f\left(x\right) = \left\{\begin{cases}\log_{e}x, & x > 0 \\ {e}^{- x}, & x \le 0\end{cases}\right) and g\left(x\right) = \left\{{x,x≥0ex,x<0\begin{cases}x, & x \ge 0 \\ {e}^{x}, & x < 0\end{cases}\right). Then, gof:R→Rgof: R \to R is:

Let f: R → R and g: R → R be defined as f(x) = \ cases _ e x, & x > 0 e ^ - x , & x ≤ 0 cases ) and g(x) = \ cases x, &

Options

  1. Aone-one but not onto
  2. Bneither one-one nor onto
  3. Conto but not one-one
  4. Dboth one-one and onto

Correct answer

B. neither one-one nor onto

Step-by-step solution

Given: f\left(x\right) = \left\{\begin{cases}\log_{e}x, & x > 0 \\ {e}^{- x}, & x \le 0\end{cases}\right) and g\left(x\right) = \left\{{x,x≥0ex,x<0\begin{cases}x, & x \ge 0 \\ {e}^{x}, & x < 0\end{cases}\right)

⇒ g\left(f\left(x\right)\right) = \left\{\begin{cases}f\left(x\right), & f\left(x\right) \ge 0 \\ {e}^{f\left(x\right)}, & f\left(x\right) < 0\end{cases}\right)</p><p>⇒ g\left(f\left(x\right)\right) = \left\{{e−x,(−∞,0]elog⁡x,(0,1)log⁡x,[1,∞)\begin{cases}{e}^{- x}, & \left(- \infty, 0\right] \\ {e}^{\log x}, & \left(0, 1\right) \\ \log x, & \left[1, \infty\right)\end{cases}\right)

Graph of g(f(x))g\left(f\left(x\right)\right) is given below:

Let f: R → R and g: R → R be defined as f(x) = \ cases _ e x, & x > 0 e ^ - x , & x ≤ 0 cases ) and g(x) = \ cases x, &

Range of gg\left(f\left(x\right)\right) = [ 0, \infty ) \neCodomain

So, g(f(x))g\left(f\left(x\right)\right) is many-one and into.

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