Question

Write (and draw the graph of) a function which is
(a) Continuous on all points except at

Answer 1

$Y = |x^2 -1|$

is the function which is continuous and differential at all points , and non differential at exact two points. The graph can help you to understand it .

Well the graph is not drawn to scale . But it depicts the graphs non differentiability at points x=1& -1.