Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

Find the value of x for which following expression are defined: $\frac{1}{\sqrt{x-|x|}}$

Options:

So, $\frac{1}{\sqrt{x-|x|}}$ is not defined for any $x∈I$

So, $\frac{1}{\sqrt{x-|x|}}$ is not defined for any $x∈R$

So, $\frac{1}{\sqrt{x-|x|}}$ is defined for any $x∈R$

So, $\frac{1}{\sqrt{x-|x|}}$ is defined for any $x∈I$

Correct Answer:

So, $\frac{1}{\sqrt{x-|x|}}$ is not defined for any $x∈R$

Explanation:

$x-|x|=\left\{\begin{matrix}x-x=0,\,if\,x≥0\\x+x=2x,\,if\,x<0\end{matrix}\right.$

$⇒x-|x|≤0$, for all x

Thus, $\frac{1}{\sqrt{x-|x|}}$ does not take real value for any $x∈R$ 

So, $\frac{1}{\sqrt{x-|x|}}$ is not defined for any $x∈R$