\( f(x) = \begin{cases} sin3x/x, & \quad \text{when } x \text{≠ 0}\\ 1, & \quad \text{when } x \text{ = 0 } \end{cases} \)
Consider left hand limit at x = 0
Here the value of function at x = 0 is f(x) = 1 which means f(0) = 1
So
Therefore, f(x) is discontinuous at x = 0.