Show that the function f given by `f(x)={x^3+3ifx!=0 ;1ifx=0` is not continuous at `x = 0`.

Explanation

To show that the function \( f \) defined by

\[
f(x) =
\begin{cases}
x^3 + 3 & \text{if } x \neq 0 \\
1 & \text{if } x = 0
\end{cases}
...