Statement-1: If $|f(x)| \leq|x|$ for all $x \in R$, then |f| is continuous at x = 0.
Statement-2: If f is continuous, then |f| is continuous.
Answer & explanation
Correct answer: option 1
Let f be continuous at x = a. Then, for every $\in>0$, there exists $\delta>0$ such that
|f(x) - f(a)| < ∈ whenever $|x-a|<\delta$
⇒ ||f(x)| - |f(a)|| < |f(x) - f(a)| < ∈ whenever $|x-a|<\delta$
⇒ |f|(x) - |f|(a)| < ∈ whenever $|x-a|<\delta$
⇒ |f| is continuous at x = a
So, statement - 2 is true.
Now, $|f(x)| \leq|x|$
$\Rightarrow|f(0)| \leq 0$ [Replacing x by 0 ]
$\Rightarrow f(0)=0$
∴ $|f(x)| \leq|x|$
$\Rightarrow|f(x)-f(0)|<|x-0|$ [∵ f(0) = 0]
$\Rightarrow|f(x)-f(0)|<\epsilon$ whenever $|x-0|<\delta(=\epsilon)$
$\Rightarrow f(x)$ is continuous at x = 0
$\Rightarrow|f(x)|$ is continuous at x = 0 [Using statement - 2]
Hence both the statements are true and statement - 2 is a correct explanation for statement - 1.