Q112 / 155 · WBJEE 2024 · Mathematics

The function $f: \mathbb{R} \rightarrow \mathbb{R}$ defined by $f(x)=e^x+e^{-x}$ is

  • A
    one-one
  • B
    onto
  • C
    bijective
  • Correct answer
    D
    not bijective

Solution

$\begin{aligned} & \text { Hint: } \because \mathrm{f}(\mathrm{x}) \text { is even function } \quad \therefore \text { Not one-one } \\ & \because \mathrm{e}^{\mathrm{x}}+\mathrm{e}^{-\mathrm{x}} \text { can't be negative } \quad \therefore \text { Not onto }\end{aligned}$

Hence, the correct answer is option: 'D'.

Relevant Questions