(a) If $$f(x)=\left\{\begin{array}{ll}x^2, & \text { if } x \geq 1 \\ x, & \text { if } x<1\end{array}\right.$$, then show that $$f$$ is not differentiable at $$x=1$$.

OR

(b) Find the value(s) of '$$\lambda$$', if the function

$$f(x)=\left\{\begin{array}{cc} \frac{\sin ^2 \lambda x}{x^2}, & \text { if } x \neq 0 \\ 1, & \text { if } x=0 \end{array} \text { is continuous at } x=0 .\right.$$