Q75 / 180 · KCET 2017 · Mathematics
Let \( f: R \rightarrow R \) be defined by \( f(x)=x^{4} \), then
- A\( \mathrm{f} \) is one-one and onto
- B\( \mathrm{f} \) may be one-one and onto
- C\( \mathrm{f} \) is one-one but not onto
- Correct answerD\( \mathrm{f} \) is neither one-one nor onto
Solution
Given that, $f: R \rightarrow R$ and $f(x)=x^{4}$
Since, $f\left(x_{1}\right)=f\left(x_{2}\right)$
$\Rightarrow x_{1}=\pm x_{2}$
So, $f(x)$ is not one-one function.
Let $y=x^{4}$
$\Rightarrow x=\sqrt[4]{y}$
or $\Rightarrow y=\sqrt[4]{\chi}$
and $\Rightarrow \sqrt[4]{x} \notin R$
So, $f(x)$ is not onto function.
Hence, the correct answer is option: 'D'.