Q. Let $f(x) = \left\{ \begin{array}{r} 5^{1/x},\ \ x < 0 \\ \lambda\lbrack x\rbrack,\ \ \ \ x \geq 0 \end{array} \right.\$ and $\lambda \in R$, then at $x = 0$

A) $f$ is discontinuous
B) $f$ is continuous only, if $\lambda = 0$
C) $f$ is continuous only, whatever $\lambda$ may be
D) None of the above
Explanation

(c)
$\lim_{x \rightarrow 0^{+}}\ f(x) = \lim_{x \rightarrow 0^{+}}\ \lambda\lbrack x\rbrack = 0$
$\lim_{x \rightarrow 0^{-}}\ \ f(x) = \lim_{x \rightarrow 0^{-}}\ \ 5^{1/x} = 0$
And $f(0) = \lambda\lbrack 0\rbrack = 0$
$\therefore\ f$ is continuous only whatever $\lambda$ may be

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.