What is the curvature of a graph at a point?

[deba123]

Consider the curve which is graph of a smooth function $$ f : (a,b) → R$$. Show that at any $$ {x}_{0}\:s.t\:{x}_{0} ∈ (a,b)$$ the curvature is $$\frac{{f}^{''}({x}_{0})}{{(1+{{f}^{'}({x}_{0})}^{2})}^{3/2}}$$.

 

[MarkFL]

Can you show us what you've tried so far so we know where you are stuck and can offer better help?